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Buitreraptor gonzalezorum: A Look at Dromaeosaur Feeding Styles.

Size: 4.3 feet (1.3 meters).

Time Period: The Cenomanian-Turonian Stage of the Early Late Cretaceous.

Locale: The Candeleros Formation of Argentina.

Name: The generic name means “vulture-roost thief,” from the Spanish buitre, which means vulture. The area where its remains were found is named La Buitrera, which literally means “vulture roost.”

 The dromaeosaurs are now some of the most iconic theropods, thanks to the frequent documentary and movie portrayals of creatures such as Velociraptor. In every portrayal, the dromaeosaurs are depicted as big-game hunters of some kind. In Walking With Dinosaurs, a duo of Utahraptor hunt Iguanodon (disregarding that this was set in Europe, where Utahraptor was never even found). Deinonychus are always shown jumping onto the flanks of Tenontosaurus that just happen to be hanging around. Velociraptor is always beating the tar out of Protoceratops, or (in extreme cases) hunting little kids. But as I’ve said before, groups are capable of having more than one main niche.

 A case in point is the more poorly known subfamily of the Dromaeosauridae, Unenlagiine. They probably lived in South America even before the continents split, and didn’t end up becoming as major faunal components as their northern relatives. They evolved short arms, flattened, small and unserrated teeth, and a very elongated body. Buitreraptor, a rooster-sized unenlagiine, is the earliest known representative of its family. The unenlagiines were probably creatures that adapted to a different niche than Velociraptor, Utahraptor, or any other dromaeosaurids due to the isolation of South America at the time. It’s possible that the small-predator roles filled by small dromaeosaurids in the Northern Hemisphere were already filled by the noasaurid ceratosaurs, provoking this unusual evolutionary side-road.

 The teeth of Buitreraptor are very telling in terms of what niche it probably occupied. While more famous theropods like Tyrannosaurus, Allosaurus, and even Velociraptor had teeth with steak-knife serrations for cutting meat and attacking larger prey, Buitreraptor’s teeth lacked such serrations, and consequently looked similar to the teeth of modern alligators and crocodiles, as well as another famous theropod, Spinosaurus. This is a hint that Buitreraptor, and even its almost 6-meter long relative Austroraptor, ate prey that was smaller than them. They may have eaten small lizards, baby dinosaurs, or even fish. The long snout of these animals, combined with the unserrated teeth, actually parallels the feeding style of the spinosaurs. I wouldn’t be surprised if unenlagiines were found with fossils of fish or small animals near them.

 The unenlagiines weren’t limited to South America, either. Rahonavis of Madagascar is another representative of the family, and some features of its body suggest that it had a volant lifestyle. This shows that flight was presumably lost in the ancestors of Rahonavis, but then re-evolved flight, probably to exploit niches that were open in the island environment of Madagascar. Like I’ve mentioned before, the Unenlagiine also contained giants like Austroraptor, which seemed even more like the spinosaurids than Buitreraptor did. Unidentified dromaeosaurid-like teeth from Australia may be attributable to unenlagiines.

So, Buitreraptor is no big-game hunter. There should be no illustrations of it leaping on the flanks of some innocent dinosaur or running around the heels of its titanosaurian contemporary Andesaurus. Its possible fish-eating lifestyle shows that the dromaeosaurids diversified in unpredicted ways because of their isolation. These dinosaurs are fairly rare in the fossil record, and if we find more remains of the unenlagiines, you can be sure that I’ll be back on this blog talking about them, and I’ll mention this post while I do it.

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Lurdusaurus arenatus: Hippopotamus Mimic?

Size: 22 Feet (6 Meters)

Time Period: The Aptian Stage of the Early Cretaceous, about 121-113 million years ago

Locale: The Elrhaz Formation of Niger

Name: Lurdusaurus is derived from the latin lurdus, meaning heavy. The specific name arenatus means sandy, like the desert that the dinosaur was discovered in.

When you look at a prehistoric animal’s skeleton, it’s often hard to tell what it used ots apparent adaptions for. Lurdusaurus is an animal whose adaptions seem interesting, but were never gone over in great detail. With Lurdusaurus, this exact thing happened. In 1965, the animal was discovered in the Tenere Desert, and the name “Gravisaurus tenerensis” was used in its first description in 1988. The name remains invalid and was never published with a description. It wasn’t until 1999, a full 34 years after the animal’s remains were first discovered, that the animal was named Lurdusaurus by Taquet and Dale Russel. Even now, there remain only a few good reconstructions. There’s one by Luis Rey and one by Pete Buchholz. Luis Rey’s reconstruction (above the text of this post, in fact) is in a 3/4 or front view, making it hard to work out the anatomical proportions. Buchholz’s reconstruction (also above the text, what a coincidence) is in a profile view and conveys the animal’s proportions pretty well. Speaking of its proportions…

Lurdusaurus was a fairly low-slung animal, and may have looked somewhat obese. The bottom of its belly could have been as low as 2 feet (0.7 meters) above the ground at times. In its feet, its metatarsals had no contact with one another, indicating that the animal’s toes were splayed and that it possibly had a single foot pad under them, which would have completely prevented them from running.  The animal’s innermost digits on each hand were reduced to a mere conical claw, which would have been used for defense from predatory contemporaries such as Suchomimus and Kryptops. It had a low center of gravity, so it could have spun around easily to stab at attackers using its hands. Lurdusaurus also had a long neck, which, combined with its strange limbs, meant that Lurdusaurus had a similar build to a small sauropod, like its contemporary Nigersaurus.

What do these features mean? They mean that Lurdusaurus was possibly aquatic. Though the splayed limbs and stocky build of this dinosaur may have simply been adaptions to support its large weight, hippopotamuses (hippopotami, whatever) lead a similar lifestyle with similar adaptions. It could be that Lurdusaurus grazed happily on water-growing vegetation, extending its long neck to crop off growths of plants. It may have even used its limbs to ‘pole’ itself along a bank in the manner of hippos today. Its main enemies would have then been crocodiles, who it would have possibly tried to defend against by simply getting out of the water.

It shared its environment with Ouranosaurus, and both were advanced iguanodonts. Their vastly different adaptions, plus their classification as Hadrosauriformes, meant that at least some advanced iguanodonts were diversifying right before the advent of the hadrosaurs. Who knows? Perhaps they would have continued to do so if not for their equally successful cousins. Though this may have been so, we still do not know why the iguanodontians were more morphologically diverse than their descendants. The hadrosauroid body plan was fairly unchanged throughout their existence, with the Italian Tethysyhadros perhaps deviating the most from it. Lurdusaurus represents a funny-looking dinosaur oddball, but its existence is beleaguered by a lack of information and reconstructions on it. Maybe someday, this creature will get its day in the limelight.

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Chirostenotes pergracilis: Oviraptorids in America.

Size: 6.6 feet (2 meters) long.

Time Period: The Campanian Stage of the Late Cretaceous.

Locale: The Dinosaur Park Formation of Alberta, Canada.

Name: The generic name means “narrow-handed one.” The specific name means “thoroughly gracile,” in reference to the animal’s slim build.

The oviraptorosaurs are actually an interesting group that I’ve started to talk about lately. Though my previous posts about this group have been about primitive and juvenile members of this clade, this post is about a fairly derived member of the group that’s from North America for a change. That animal is Chirostenotes.

The first fossils of Chirostenotes (two hands) were found by George F. Sternberg in 1914. The specimens were studied by Lawrence Lambe, who died before naming them. Ten years after the hands’ discovey, Charles Gilmore adopted the name Chirostenotes pergracilis from Lambe’s notes. Later, feet were found and given the name Macrophalangia by Charles M. Sternberg, who believed that they belonged to an ornithomimid. The name Caenagnathus was assigned to some lower jaws (first thought to belong to a bird) found by Ray Sternberg. Caenagnathus was concluded to be an ornithomimid, Chirostenotes and Macrophalangia were found to be synonymous, and Caenagnathus was found to be an oviraptorosaurian. An Asian animal (Elmisaurus) of which both hand and feet preserved bore amazing resemblance to Chirostenotes. Another specimen was discovered and described by Phil Currie and Dale Russel,  indicating that Caenagnathus, Macrophalangia, and Chirostenotes were not oviraptorosaurians, but one in the same.

A few other specimens have been more recently referred to Chiostenotes. These specimens came from Alberta (named Ornithomimus elegans), and the Maastrichtian Hell Creek and Horseshoe Formations. The specimen from Alberta has been renamed Elmisaurus elegans. The Horseshoe specimens were renamed Epichirostenotes in 2011, and the Hell Creek specimens are still being studied. The latter specimens are both complete and very large in size.

Chirostenotes had a toothless beak and long arms that ended in slender, straight claws. The animal had powerful legs and slim toes. The animal was an omnivore or herbivore, and it probably ate small animals, plants, eggs, and insects. In 2005, a study about Chirostenotes’s hand function found that the elongated, unusually straight-clawed second finger may have been used for probing crevices like an aye-aye. The analysis suggested that Chirostenotes fed on soft-bodied animals like grubs, mammals, and reptiles, which were easy to impale with the animal’s claw. If Chirostenotes possessed large primary feathers on its second finger (which have been found in oviraptorosaurs like Caudipteryx) and wouldn’t have been able to engage in this lifestyle. I assume that the feathers on Chirostenotes’s hand were secondarily lost to help the animal skewer its prey.

Chirostenotes was mistaken for an ornithomimid at one point in its early history of discovery. Now that it’s understood to be an oviraptorosaur, we know a bit more about this group. The animal was an interesting crevice feeder in life, augmenting our knowledge of oviraptorosaurian feeding habits, and though all of its specimens aren’t positively referable to the animal, it’s an interesting animal all the same.

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Tethyshadros insularis: Freaks on an Island.

Size: 13 feet (4 meters).
Time Period: The early Maastrichtian Stage of the Late Cretaceous.
Locale: The Liburnia Formation of Italy.

Name: "Insular Hadrosaur from the Tethys." 

Islands are interesting places. They can be dangerous for people with no idea as to what to do, and they can even be the source of mad internet speculation (I’m deliberately referencing Lost). Evolutionarily, however, islands are really interesting places, and are filled with strange animals even today because of geographical isolation. Prehistoric animals aren’t exempt from the rule that animals on islands tend to evolve down different paths than those of their relatives. Charles Darwin himself studied evolution in island animals, and his finds paved the road for evolutionists everywhere. Anyway, in the Pliestocene, the Mediterranean islands were filled with dwarf elephants, where the opposite happened to dormice and owls that grew to gigantic sizes. Further back in the Mesozoic, animals either grew smaller than their large relatives (Magyarosaurus, Europasaurus) or just became plain weird-looking (Balaur). Tethyshadros is one of those dinosaurs that became weird-looking after millions of years of evolution on an island and one of those that became smaller.

As the name may suggest, Tethyshadros was a hadrosaur from the gradually receding Tethys Sea. Its anatomical features set it apart from its distant relatives, and it was also small in comparison, at only 13 feet (4 meters) long. It had a mix of primitive and advanced traits, with a long skull, short neck and tail, and legs that were long again, as well as a reduction in the number of fingers that the animal possessed. The unusual mixture of proportions suggests that this animal was adapted for bipedal running, and likely employed its speed to escape from enemies. It also probably had a spiky beak over its equally spiky denticles. In one of the above illustrations, this shows just how bizarre the animal may have looked. They may have been a feeding adaption, or they could have been used for grooming or display functions. I don’t know either. Anyway, Tethyshadros has a very distinctive anatomy for a hadrosaur, whose characteristics seem more suited to facilitative bipedalism.

Phylogenetically, Tethyshadros appears to be related to the Hadrosauridae and more closely to Telmatosaurus. This is no surprise, seeing that they were both dwarf hadrosaurs from Europe that lived at roughly the same time. The presence of these animals on the islands of Europe has been explained by paleontologist Dalla Vecchia, who says that basal hadrosauroids island-hopped from Asia to Europe and then evolved independently from their Asian and American contemporaries. Vecchia also said that the possibilities that the European hadrosaurs are relicts of isolated evolution from their earlier European relatives or are descended from their aforementioned American contemporaries are not valid. Either way, the animals did evolve on their own on islands, leading to some bizarre features.

Anyway, animals like Tethyshadros are funny-looking, and while they may resemble their more famous relatives, they certainly do look different. The fact that Europe was not one continent but rather a series of tectonically volatile islands shows that their dinosaurs would have been as strange as other isolated island creatures of the past and present. We may not know how they all looked, but island dinosaurs are surely very interesting simply because of the looks of those we do know.

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Tianyulong confuciusi: More Tiaojishan dinosaurs.

Size: A bit less than 6.6 feet (2 meters)

Time Period: The Oxfordian Stage of the Late Jurassic.

Locale: The Tiaojishan Formation of China’s Liaoning Province.

Name: “Confucius’s dragon of Tianyu (Tianyu is part of the name of the Shandong Tianyu Museum of Nature where Tianyulong’s holotype is housed).

Some dinosaur discoveries are not very notable, and don’t do much to increase our understanding of dinosaur phylogeny or distribution. Hey, look, somebody discovered another titanosaur in South America. Some do increase our understanding of these things, and are very cool discoveries. Still others forever change the way we look at dinosaurs. Tianyulong was one of those discoveries. The biogeographical implications of the creature were soon overshadowed by other things, however.

You see, Tianyulong possessed feathers. An ORNITHISCHIAN DINOSAUR (not part of the lineage including birds) HAD PROTOFEATHERS. As you can expect, the media flipped its collective top upon hearing of this. In fact, this wasn’t that big of a discovery. As of recently, we knew that the primitive ceratopsian Psittacosaurus had quills on its tail. People speculated that many ceratopsians were feathered as a result, and now that is a growing trend. However, it was still pretty big. Here’s why. Tianyulong is a heterodontosaurid, a very primitive ornithischian whose relatives occurred in the Early Jurassic. In fact, its feathers were more primitive than those of saurischians like Beipaiosaurus. The fact that such a primitive creature had feathers is astounding, mainly because it hints at the hypothetical common ancestor of pterosaurs and dinosaurs having feathers.

However, some have argued that there is an alternative. It’s possible that the occurrence of feathers evolved independently in ornithischians, saurischians, and pterosaurs, and that their common ancestor was completely naked. The fact that Tianyulong’s and Beipaiosaurus’s protofeathers were differently shaped in cross-section (with those in the former being round and the latter’s being flat) and that they were such radically different lineages may prove this. In fact, Tianyulong’s feathers are the shape that was predicted for the most primitive kinds of feathers, further alluding to this dinosaur’s primitive nature. I still think that the common ancestor of these groups had feathers, because it seems more likely and makes it more fun to illustrate more primitive forms.

Finally, Tianyulong’s time period has been questioned. It was originally thought to have belonged to Yixian Formation strata, which would have made it an Early Cretaceous heterodontosaurid and the latest-surviving member of the group. Further dating showed it to be in the Tiaojishan Formation of the Early Late Jurassic, just like Eosinopteryx (The last dinosaur I blogged about, coincidentally). This coincides with the time periods during which most other heterodontosaurids existed. Also, Tianyulong being found in Late Jurassic Chinese strata proves that heterodontosaurids had achieved a global distribution by this time.

That’s all I have for now. Though you may feel that Tianyulong is overrated because of its intense media exposure, I just wanted to voice my own thoughts about this unique and awesome dinosaur.

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Raptorex kreigsteini: Two-Fingered Tyrants of… The Early Cretaceous?

Size: 8.2 feet (2.5 meters) long.

Time Period: The Time Period is disputed, and Raptorex may be from either the Early or Late Cretaceous.
Locale:
Again, disputed. It could be from the Early Cretaceous Yixian Formation of China, or (now considered more likely) from a Late Cretaceous Mongolian Formation like the Iren Dabasu Formation.

Name: The generic name means “robber king,” and may refer to the specific name of Tyrannosaurus rex. The specific name refers to holocaust survivor Roman Kreigstein, whose son donated the specimen to the University of Chicago for scientific study.

 If there’s one thing that Tyrannosaurus rex is really considered weird for in pop culture, it’s the animal’s puny arms. With two fingers apiece, the little arms were very vestigial and practically useless in the pursuit of prey (though not as useless as those of the abelisaurids). There’s more to the arms than the most derived carriers of them, however. It makes one wonder: how did these two-fingered arms come into fruition? 

Enter Raptorex, a tyrannosauroid from the Early Cretaceous of China. Unlike its contemporaries, Raptorex possessed the vestigial fingers of Cretaceous tyrannosaurines. It was a very small, slender form, described as an adult by Paul Sereno and company. The distinct anatomy of Raptorex was shared with giants like Daspletosaurus and Zhuchengtyrannus, and consisted of a large head, long legs, and tiny two fingered arms. This contradicts previous hypotheses that the characteristic body shape of Tyrannosaurus and its relatives only evolved after giant size in the group. All previously known primitive tyrannosaurs had small skulls and long, three-fingered arms, including both species that lived at the same time as Raptorex and slightly later ones. This find radically alters our entire view on how the body shape of the tyrannosaurids evolved… 

…Which is what I would say if I weren’t too busy psyching you out. See, since the description of our pal the robber king, our interpretation of what it truly was has changed a good deal. Since the place of discovery isn’t originally known, Paul Sereno was forced to try to date it using index fossils (more on that later), which he found indicated that Raptorex was from the Early Cretaceous of China. Now, we think that it wasn’t from that area or time at all. Truth be told, it was probably from the Late Cretaceous of Mongolia, where two-fingered tyrannosaurids were large and in charge. One of the bases for this assumption is the probable incorrectness of the index fossils used to date Raptorex. The fish vertebrae identified as belonging to the genus Lycoptera and the crushed mollusk shell that served the purpose as index fossils are actually no help at all in dating the animal’s remains. As the mollusk shell is crushed and unidentifiable, it obviously serves no purpose as an index fossil. As for the Lycoptera fossil, it’s not really a Lycoptera at all. The fish bone identified as a Lycoptera is different in shape and much larger than any known specimen referred to this genus. Instead, it probably belonged to an ellimmichthyiform fish. This kind of fish spanned the entire Cretaceous period, making this bone useless as well. Combine these facts with the uncanny resemblance of Raptorex to juvenile tyrannosaurids, it’s very likely that the animal is simply a juvenile representative of Tarbosaurus or some other derived tyrannosaurid from Mongolia.

 It’s a shame that Raptorex’s true nature is so underwhelming. Though it may seem like science has ‘crushed our dreams’ or whatever, it’s still a very well-preserved find that represents one of the first juvenile tyrannosaurs known from Asia. As for where and when that strange two-fingered hand originated in the fossil record, I have absolutely no idea. Only time will tell. Aaaand expect for me to reference this post if some find like that actually comes up. I’ll be waiting.

 

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Torosaurus latus: Triceratops or Not?

Size: Roughly 25 feet (8 meters) long.

Time Period: The Maastrichtian Stage of the Late Cretaceous Period. This animal was one of the last of the ceratopsids, and one of the last dinosaurs in general.
Locale:
The Javelina, Frenchman, Lance, and Hell Creek Formations, all found in the western United States of America.

Name: The generic name means “Perforated lizard,” in reference to the holes (fenestrae) in the animal’s frill. Though most people assume that the name means “Bull lizard (from the Latin noun Taurus),” such a meaning would entail a spelling such as “Taurusaurus” or “Taurosaurus,”  the name is probably derived from the Greek verb toreo, which means “to perforate.” A lot of the confusion about the meaning of the name has to do with the fact that Othniel Charles Marsh (the original describer) wasn’t specific about the origin of the name.

Triceratops, one of the most famous dinosaurs, was a common animal in its time and place, and outclasses all Maastrichtian ceratopsids in range, population, and (of course) popularity. Animals like Anchiceratops, Arrhinoceratops, and Torosaurus were way more common, but still important. Anyway, Torosaurus was a very large ceratopsid discovered in 1891, two years after the initial discovery of Triceratops. It, unlike Triceratops and like most other known chasmosaurines, possessed a very long frill that had two large holes (also called fenestrae), which had no use in defense and was probably used for courtship displays.

Aside from being really flashy and cool-looking (probably the reason why Torosaurus was in Walking With Dinosaurs instead of Triceratops), there is a major controversy surrounding Torosaurus and its phylogeny. Since its discovery, Torosaurus has been recovered as a very derived member of the tribe Triceratopsini, and was most closely related to Eotriceratops and Triceratops. This pattern was shattered in 2010, when a histological study indicated that Torosaurus may have simply been the mature form of Triceratops. Jack Horner noted that ceratopsian skulls consist of a kind of bone that may lengthen or shorten over time, and may change from one shape to another over time. Part of the reassignment of Torosaurus is confusing, considering how much variety is seen in Triceratops skulls (which have historically been assigned to many genuses and species). Horner observed that roughly half of all known subadult Triceratops specimens possessed two thin areas in the frill that may have corresponded with the placement of the holes (FENESTRAE!!) in a Torosaurus’s frill. This might suggest that the holes developed to lighten the load of the skull as the animal (and its colossal frill) grew.

Other researchers are less sure about this idea than Horner and Scanella. I personally think that the supposed status of Torosaurus doesn’t explain some crucial facts, such as the extremely uncommon nature of Torosaurus remains relative to those of Triceratops. It’s also asserted that distinct juvenile specimens of Torosaurus were found in the Javelina Formation of Texas. These animals have been strongly identified as Torosaurus. In Triceratops, the thin areas of the frill actually differed in shape and position from the holes (fenestrae) found in the frills of Torosaurus. A 2011 analysis by Andrew Farke also noted that the development of Triceratops into Torosaurus would require unusual bone development and the unprecedented establishment of holes (fenestrae) in the frill late in the animal’s life.

In short, Torosaurus has sometimes been classified as an adult specimen of Triceratops. Even if this were true, the genus Triceratops would be valid (not ‘dead’ as discussed by the media in 2010), having been discovered 2 years prior to Torosaurus. Considering that the analyses of Andrew Farke in 2011 and of Nicholas Longrich in 2012 present data that outweighs the 2010 hypothesis, I’m going to assume that Torosaurus and Triceratops are distinct (though related) forms and leave it at that.

(I hope you forgive me for my copious use of the term fenestrae, incidentally.)

First of all, I’m back. Second of all, you probably recognize this picture. It’s of Nasutoceratops titusi, a ceratopsid that wasn’t formally described the last time(s?) that I talked about it. Fans of ceratopsids will be pleasantly surprised to know that Nasutoceratops has been formally described, so I can talk about it with more certainty. Yay.

Nasutoceratops comes from the Campanian stage of the Late Cretaceous, and is from the Kaiparowits Formation of Utah. Looking at this dinosaur, one might assume that it’s related to Triceratops or Chasmosaurus, but it isn’t. Incidentally, its skeletal elements looked something like this:

From these skeletal elements, it’s been concluded that Nasutoceratops is a centrosaurine ceratopsid, and is most closely related to Avaceratops lammersi, another primitive centrosaurine with brow horns. However, Nasutoceratops is unique because its horns have an arrangement remarkably similar to that of modern bovines. These horns may have played a role in display or interspecies combat.

Near Nasutoceratops’s left shoulder, skin impressions were found. One of these impressions shows large hexagonal scales surrounded by small, triangular scales. This is reminiscent of the scale arrangement in other ceratopsians, which have similar geometric patterns.

The fact that Nasutoceratops exists is proof of the separation between the Northern and Southern fauna of Larimidia (what is now western North America). It retained long brow horns and a short (nearly unnoticeable in Nasutoceratops’s case) nose horn, contrary to the ornamentation of its northern kin. It may be a representative of a previously unknown clade of centrosaurines whose remains aren’t yet known.

Lastly, the origin of Nasutoceratops’s name is a bit convoluted. Devout fans of new dinosaur discoveries have probably heard the name Nasutuceratops, and are probably very confused thanks to my use of Nasutoceratops. The generic name of this dinosaur is derived from 'nasutus,' the Latin word for ‘big-nosed,’ as well as 'ceratops,' which is Ancient Greek for ‘horned face.’ The specific name, titusi, honors Alan Titus, the man who recovered fossils of Nasutoceratops.

Well, this was an interesting post. I do enjoy going back to old topics and revisiting them. This time, the post was tied in with the series I’ve been doing on new 2013 discoveries. 

Remember to send requests for posts.

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Minotaurasaurus ramachandrani: The Mysterious Skull.

Size: 16.4 feet (5 meters) long.
Time Period:
Unknown, presumably the Late Crecaceous Period.
Locale:
Unknown, probably recovered from the Gobi Desert.
Name:
The generic name means “Minotaur lizard,” in honor of the animal’s distinctive skull. The specific name honors Vilayanur S. Ramachandran, who purchased the fossil from a trader and made the animal recognizable in the scientific community.

In modern days, more and more dinosaur specimens are being unearthed from places all over the world. The more fossils are being unearthed, the more likely it is that some will be distributed without the proper form of documentation. A case  of this improper documentation is found in Minotaurasaurus, a distinctive and really well-preserved fossil whose origins may forever remain a mystery.

Where this skull comes from is still very often debated, and there have been conflicts about who should keep it. As I mentioned above, Vilyanur Ramachandran purchased the holotype specimen in Tuscon, Arizona from a fossil trader named Hollis Butts for ten thousand dollars. Though we know how the fossil was made known, we don’t know exactly where it originated. Some people claim that the fossil was removed from the Gobi Desert without the permission of any government and sold sans documentation, an action which, as you may guess, is frowned upon. Ramachandran has no problem with giving the fossil to its proper nation (probably Mongolia or China) if he is shown evidence of the specimen being exported without a permit and without documentation. As of January 2013, the specimen is in a museum in California, as shown in the picture above.

The animal is known only from a skull, but one that is distinctive enough to merit its own genus, as well as a distinctive name. Though Tom Holtz says that this may be a species of Pinacosaurus and others say that it could be a species of Saichania, both being other species of ankylosaur, I think that it would be prudent to wait for proper understanding of the age of the fossil and where it was really found before such classification occurs. Anyway, Minotaurasaurus’s generic name was inspired by the Minotaur, the mythological monster with the body of a man and the head of a bull. Like its relatives, Minotaurasaurus possessed the kind of hornlets present in other ankylosaurids, but these were very elongated and extended further behind the skull than those of its relatives. Further information regarding this animal pertains to its braincase, which was primitive compared to those of its previously mentioned relatives. Apart from that, its characteristics appeared to be standard for an ankylosaurid of its presumed age of the Later Late Cretaceous. It’s very likely that the animal was found in the Gobi Desert of either China or Mongolia, but given the lack of documentation about the specimen, I conclude here that it may have originated in North America. We may never know.

Since its braincase was more primitive than some of its relatives’, it’s possible that the animal was found  earlier in the Late Cretaceous than Ankylosaurus or even Euplocephalus. Though I doubt that the fossil is older than the Campanian Stage, I can’t exclude the possibility that it occurred even earlier than that.

So, here we have the tale of a really intriguing fossil whose origins are completely uncertain. The moral of this story is that we definitely need our documentation system, as we would be completely lost without it. It’s a really cool animal, but I wish we had more information about it.

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Agilisaurus louderbacki: Unfascinating to you, not to me.

Size: About 5.6 feet (1.7 meters) long.

Time Period: The Bathonian and Callovian Stages of the Middle Jurassic Period.
Locale:
The Lower Shaximiao Formation from the Dashanpu Beds of China.

Name: The generic name quite obviously means “agile lizard,” due to the probable cursorial lifestyle of the animal. The specific name honors Dr. George Louderback, an American geologist and the first man to recognize the presence of dinosaur fossils in the Sichuan Province of China. 

I don’t get why primitive ornithopods are so boring. They probably weren’t big enough, strong enough, weird enough, or whatever other reasons you can think of. I think they’re cool enough, and I’ll keep blogging about these little guys no matter what. 

The animal in question is Agilisaurus. This animal is known from one of the most complete small ornithischian skeletons that have ever been found. Only some bones from the left side of the body weren’t found, and those can be reconstructed from the bones found from the right side of the specimen. 

Despite the near-complete skeleton of Agilisaurus, the animal remains an enigma of sorts. We know that it was a small, two-legged ornithopod, but that description is obviously fallible, and can apply to anything from Pegomastax to Thescelosaurus. 

Agilisaurus was originally classified as a member of the Fabrosauridae. This group used to be far more inclusive (and contained Scutellosaurus initially), but now just possibly includes Agilisaurus, as well as the lesser-known Gongbusaurus and the very poorly known Fabrosaurus, whose fragmentary remains may actually belong to a Lesothosaurus-like animal. Most paleontologists consider the Fabrosauridae to be invalid, and so changed their minds about Agilisaurus. Agilisaurus was later found to be the basalmost representative of the Euornithopoda, which includes all ornithopods more derived than the Heterodontosauridae. There’s a fault with this placement as well, though. In my eyes (and in those of many other paleontologists nowadays), the heterodontosaurids aren’t ornithopods at all, and are probably way more closely related to the marginocephalians, the group containing ceratopsians and pachycephalosaurs. In 2006, Agilisaurus was found to be more basal to heterodontosaurs in the branch leading to the marginocephalian dinosaurs. Then it was found to be an ornithischian basal to ornithopod and marginocephalian alike.

Biology time! Firstly, I hate to stereotype here, but Agilisaurus’s sole defense was probably speed. That’s probably why its name has the word ‘agile’ right at the beginning of it. Anyway. Comparisons between the sclera rings of Agilisaurus and modern birds and reptiles indicate that the animal was diurnal (active during the day). This is unlike larger herbivorous dinosaurs that were more likely to be cathemeral (active throughout the day at short intervals). This means that Agilisaurus was probably always out and about foraging for food.

The problem with this animal isn’t the skeletal remains. It’s how poorly known all of its potential relatives are. The relationships of many primitive ornithopod clades are poorly understood simply because potentially helpful or interesting animals like Fabrosaurus are known from the worst of remains. It’s ironic that a gem of a fossil like Agilisaurus is impossible to classify. See, even a complete skeleton remains essentially useless if nothing else is known to better classify it. I hope you enjoyed this obligatory small ornithopod post. See you next time, I guess.

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Growing Pains: The Pachycephalosaurus discussion

We are now familiar with the pachycephalosaurs, dome-headed dinosaurs that are relatives of ceratopsians. Most of all, people are familiar with Pachycephalosaurus, a dome-headed dinosaur that was the largest animal in its group as well as the last. Contemporaries of this dinosaur included Stygimoloch and Dracorex, two smaller pachycephalosaurs that some are saying represent different growth stages of Pachycephalosaurus instead of separate genuses. This is an interesting theory, and its only con to me seems to be the loss of the names Stygimoloch and Dracorex, two genera names that sound more interesting than ‘thick-headed lizard.’ While I was initially skeptical about this theory, I have realized that it is fairly plausible upon looking at the skulls of this three animals and their sizes.

The growth stage theory places Dracorex hogwartsia as the youngest form of Pachycephalosaurus. Its head is not domed at all as in larger pachycephalosaurs, and its head has lots of fairly long spikes on it. It’s also smaller than Stygimoloch or Pachycephalosaurus. This would have previously placed it as a relative of the flat-headed Homalocephale, but that dinosaur is now known to be the juvenile form of Prenocephale, much as the theory I am talking about now regards Dracorex. The dinosaur was actually discovered fairly recently, and was placed under close scrutiny immediately because of its status as a contemporary and relative of Pachycephalosaurus.

Next is Stygimoloch spinifer. This pachycephalosaur has been proposed as the intermediate form between Dracorex and Pachycephalosaurus. Not only does it have a domed head like the latter, but it has smaller spikes than Dracorex. Its dome is smaller than Pachycephalosaurus’s, and it is larger than Dracorex while being smaller than Pachycephalosaurus. From this, we can deduce how this dinosaur grew. Dracorex, which had the longest spines on its head and no dome, must represent the youngest individuals of Pachycephalosaurus, whose young lost their long horns and grew domes as they got older. This idea shows us not only how pachycephalosaurs looked as they aged, but also how we must now classify flat-headed pachycephalosaurs like Goyacephale.

This is just one instance of dinosaurs not being what we think they are at first. There are lots of debates in the paleontological world about whether or not some genuses should be considered growth stages or members of other genuses, from the debates about whether some Iguanodon species should be considered separate genuses to the debate regarding whether Triceratops is just a young Torosaurus. When these things will be resolved is unknown, but from time to time reasonable answers to our questions show themselves and fit one more piece into the puzzle of dinosaur classification.

Additional note: Regarding Goyacephale, the specimen that it was named for isn’t the same as Homalocephale, although they look similar. It has different proportions from the latter, and should be considered either another growth stage of Prenocephale or evidence that some pachycephalosaurs did indeed have flat heads as adults. 

So, it could be that all pachycephalosaurs went through these growth stages, or just Pachycephalosaurus. As with all paleontological matters, we may never know without more evidence.

P.S. I told you that the European dinosaur fad was over.

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Manidens condorensis: Heterodontosaurids and Backwards Evolution.

Size: 24 to 30 inches (60 to 75 centimeters) long.

Time Period: The Bajocian Stage of the Middle Jurassic.
Locale:
The Cañadon Asfalto Formation of Argentina.

Name: The generic name means “hand tooth,” in reference to the hand-shaped posterior lower teeth. The specific name honors the village of Cerro Condor, close to where its remains were found. Other dinosaurs from this formation (e.g. Condorraptor) also bear the name of the village.

The heterodontosaurids were initially one of the most perplexing groups of ornithischian. A long time ago, all known heterodontosaurid remains were found in the Upper Elliot Formation, where they still turn up today. They left no discernible descendents, save Echinodon of the Early Cretaceous of England. Over time, we found that the group had a wider chronological and geographical range than we knew. Representatives of the group turned up in North America (Fruitadens), Asia (Tianyulong), and South America. It is the South American heterodontosaurid Manidens that I discuss here.

Manidens is known from a partial skeleton consisting of a skull and lower jaws, a left shoulder girdle, a portion of the axial column, and the pelvis. Isolated teeth from the same locality are also referred to this genus. This animal was a fairly basal heterodontosaurid that was so little that it gave the notoriously tiny Fruitadens and Pegomastax a run for their money in the size department. There’s something else interesting about this animal, however. It is a transitional form between South African forms like Lycorhinus and more advanced heterodontosaurids like Fruitadens.

According to fossil remains, Early Jurassic heterodontosaurids such as Heterodontosaurus itself possessed specific dental adaptions to a herbivorous diet. They had dental batteries and tooth facets that indicated chewing patterns that were more specific to herbivores than anything else. In contrast, later heterodontosaurids like Echinodon and Tianyulong didn’t have these specialized adaptions. The lack of tooth wear on these animals’ jaws indicated a different kind of jaw motion. This suggests that these later heterodontosaurids weren’t strict herbivores, but instead facultative omnivores and overall generalists.

Manidens looks like a transitional fossil, and represents a transition from a specialist lifestyle to a generalist one. If this is true, then the heterodontosaurids experienced a strange evolutionary pattern. They evolved out of more specialized roles, where all other herbivorous dinosaurs became increasingly specialized as time marched on.

Why did this happen? I suggest that it may have been due to competition by other herbivores, forcing heterodontosaurids to move out of plant-eating roles. By the Middle Jurassic (as Manidens indicates), heterodontosaurids were becoming less specialized. This lower level of specialization coincides with the evolution of more advanced herbivorous ornithopods, which were probably driving primitive heterodontosaurids away from herbivory. By the Late Jurassic to Early Cretaceous, all remaining heterodontosaurids (all of which were Laurasian, coincidentally) were generalists.

So, the heterodontosaurids became less specialized over time. It’s a weird trend otherwise unseen in the herbivorous dinosaur groups. This was probably due to changing faunal assemblages and the introduction of herbivores that could more efficiently get food. Manidens is important because it bridges the gap between specialist and generalist, and furthers our knowledge of the Heterodontosauridae as a group.

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Bonitasaura salgadoi: The Missing Link (Or one of them, anyway).

Size: The one juvenile specimen that was found was 23 feet (7 meters) long.

Time Period: The Santonian Stage of the Late Cretaceous Period.
Locale:
The Bajo de la Carpa Formation of Argentina.

Name: The generic name means “La Bonita lizard,” in reference to “La Bonita,” the quarry where it was found. The specific name honors Leonardo Salgado, an Argentinian paleontologist of great renown.

This is another sauropod skull post. Like my posts about Abydosaurus and Tapuiasaurus, it’s about the animal’s skull and what it means. Also like these posts, it’s about a macronarian, that famous lineage leading to dinosaurs like Saltasaurus and Giraffatitan.

This animal’s remains are from a partial sub-adult skeleton found in sandstone. Remarkably, this animal is preserved with a skull that resembled that of the diplodocids. This skull’s lower jaw had a sharp ridge set behind a reduced set of teeth. The ridge may have supported a sheath not unlike a beak, which probably had a counterpart in the upper jaw. The sheath would work in tandem with the peg-like front teeth in order to rake vegetation into the mouth and then crop it. Interestingly, Bonitasaura was the only sauropod known to have a beak.

The neck of Bonitasaura was short, and its back vertebrae had projections for muscle attachment. This indicates that the neck was often used intensively during feeding.

Bonitasaura’s skull resembles that of some diplodocid sauropods, animals that titanosaurs were often confused with in the past. Some titanosaurians exhibited long, low skulls without the nasal arches of other macronarians like Brachiosaurus. The lower jaws of these titanosaurians were squared off with comb-like teeth. The titanosaurians resembled diplodocids in their limb proportions and whip-like tails. Bonitasaura permits the recognition of square jaws in a titanosaurian. It also had a peculiar skull shape that increases the known diversity of titanosaurian skulls. The known skulls belong to Rapetosaurus, Nemegtosaurus, and Tapuiasaurus. Unlike the skull of Rapetosaurus, the skull of Bonitasaura is short from front to back and rather tall, resembling the skulls of more basal macronarians, such as Camarasaurus and Malawisaurus. The skull of Rapetosaurus is long and low.

Despite its resemblance to diplodocids, Bonitasaura was a titanosaurian. It was related to mid-sized to large titanosauroids that lived during the Turonian and Campanian stages of South America, and not (as was previously believed) to the nemegtosaurids of the Northern Hemisphere.

The strong resemblance that Bonitasaura bore to the diplodocids shows that titanosaurians rushed in to fill niches left by their extinction. Titanosaurs and diplodocoids may have even competed for food and other resources before the extinction of the latter. Though I said in my post with Tapuiasaurus that the resemblance between Tapuiasaurus and Rapetosaurus indicates that they didn’t need to evolve, and thus didn’t compete with diplodocids as much. I believe that this might have been misconstrued, as I was referring to the one group. Along with the diplodocid niche, titanosaurs took over the niches of all other sauropods (and in the south, all large herbivores).

The titanosaurs are a group whose skulls are poorly known. Still, another skull being found is surprising. Bonitasaura is bizarre, because it doesn’t resemble many of the other titanosaurs whose skulls are known. It had a strange beaked skull which would have sheared and raked plants like their bygone cousins, the diplodocids. These dinosaurs were long-gone by the time the titanosaurs had achieved complete dominance, but their looks and feeding habits were reflected in animals like Bonitasaura, descendant of the animals that ousted them from their feeding niches.

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Shantungosaurus giganteus: The Largest of the Ornithopods.

Size: Its synonym Zhuchengosaurus reached the huge size of 54.5 feet (16.6 meters) long.

Time Period: The Campanian to Maastrichtian Stages of the Late Cretaceous.
Locale:
The Wangshi Formation of China.

Name: The name refers to Shandong Province of China, where it was found. The specific name refers to the animal’s gigantic size, of course.

Possibly one of the most attention-grabbing things about dinosaurs is the spectacular size of some of these animals. Animals like Brachiosaurus, Triceratops, and Giganotosaurus are very publicized simply because of how big they are. Here, I talk about possibly the most underrated of all giant dinosaurs, an ornithopod named Shantungosaurus. 

This animal is the largest known ornithischian and the largest non-sauropod dinosaur of all (The latter depends on which size estimate of Spinosaurus you think is valid). I’ve discussed extraordinarily large ornithopods before (Charonosaurus, Velafrons), and have as yet failed to find a concrete reason why. In Mexico, it may have been due to climate factors, but in Asia, it may have been different. This may be because of the absence of other truly gigantic herbivores in Shantungosaurus’s environment or something else entirely. 

One of the most distinct features of Shantungosaurus was its unusually long tail. This tail is deep and flattened from side to side like the tail of a crocodile. This was initially thought to be evidence enough that hadrosaurs like Shantungosaurus spent most of their time in the water and used their tails for swimming, almost like those of crocodiles. This was later disproved, as the tail vertebrae of Shantungosaurus were lashed together with ossified tendons. Unlike those of true aquatic animals, the vertebral spines above and below the tail vertebrae sloped backward. In crocodiles and other aquatic animals, the spines are vertical and provide strong attatchment points for swimming muscles. The tendons were like those of the hypsilophodonts and dromaeosaurs, which needed these to keep their tails off of the ground and run. Considering the weight of Shantungosaurus, the tail was probably not used to stiffen the tail while running. You have to consider that Shantungosaurus walked on two legs at times (being earth’s largest biped), and that the tail probably acted as a counterbalance for the massive weight of the body. 

A large hole found near the nostrils of the animal may have been covered in a loose, potentially inflatable flap that could have been used to make loud noises for communication. 

Phylogenetically, Shantungosaurus similar to and shares many unique derived characteristics with Edmontosaurus, one of the most common of all dinosaurs in the Late Cretaceous of North Ameica. These animals form an Asian node containing Edmontosaurus and Shantungosaurus alone. This is because of faunal interchange, a topic that I’ve already spoken about at unbearable length. Remains of several individuals were found in Shandong, China once again. They were then classified into a new genus and species called Zhuchengosaurus maximus, a genus later proven synonomous with Shantungosaurus. All supposedly distinct features of Zhuchengosaurus were actually results of these remains being from different growth stages. 

So, the giant dinosaurs aren’t always as glamorous as they seem. Though ornithopods often seem like the most drab of all dinosaurs (even to me sometimes), they can be as interesting as their various relatives (in fact, expect me to do a post on another ornithopod soon. I’m thinking Blasisaurus).

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Europasaurus holgeri: Cow-Sized Sauropods.

Size: 20.3 feet (6.2 meters) long.

Time Period: The Kimmeridgian Stage of the Late Jurassic.
Locale:
An unnamed formation in Northern Germany.

Name: The generic name means “Europe lizard,” and the specific name honors Holger Lüdtke,who discovered the first fossils of Europasaurus.

The sauropods are often thought to be either large or completely colossal. What most people don’t know is that they can also be very small in size. Here’s a sauropod that’s actually very small in size, and not at all as big as Sauroposeidon and Paralititan.

Said dinosaur is Europasaurus, a member of the Brachiosauridae. A 2012 analysis revealed it to be the most basal known member of this family. One other analysis regarded it as the sister group of the Brachiosauridae and more derived Titanosauriformes. Europasaurus’s skull has also been compared to that of the very well-known Camarasaurus. Europasaurus had a longer postorbital and a shorter nasal-frontal contact compared to its more basal relative. Compared to Brachiosaurus, Europasaurus had a shorter head, among other things. It was also compared to fellow European macronarians such as Lusotitan (of the same formation as Miragaia) and some remains formerly referred to the wastebasket taxon Cetiosaurus. Europasaurus can be distinguished from nearly all of its fellow neosauropods because of its extremely small size.

About that size, now. Europasaurus has been shown to represent a dwarf species as opposed to a juvenile representative of some other genus. In another comparison with Camarasaurus, bone histology of Europasaurus shows that the tiny size of Europasaurus was the end result of a decreased growth rate. Other sauropods have a very accelerated growth rate, which was needed in order to facilitate the transition from tiny to huge in these kinds of dinosaur. Dwarfism in macronarians actually seems highly unusual, considering that the clade Macronaria contains some of the (if not the) largest dinosaurs.

The small size of Europasaurus is probably due to its island habitat. Even the largest of the islands in the Lower Saxony Basin (where it was found) were less than 2,000 square kilometers in size. It’s been suggested that, in order to cope with living in such a restricted habitat, the ancestor of Europasaurus adapted to this environment very quickly to prevent its kind from dying out. Europasaurus is considered an insular dwarf, a large animal that has grown smaller in an island environment. This isn’t unique in dinosaurs or even in large animals, as dinosaurs from the Late Cretaceous of Romania were small too. Telmatosaurus and Magyarosaurus (a hadrosaur and titanosaur, respectively) were very petite compared to larger members of their groups. In Hateg Island, dinosaurs became small for precisely the same reason. Note: Though macronarians are the only sauropods known to show dwarf variants so far, this is probably due to sampling bias. I assume that dwarf diplodocoids will eventually be found from Late Jurassic island sediment. It’s probable that Europasaurus’s primitive nature is due to its isolation, as more derived brachiosaurids (Lusotitan) have been found from the same time in Europe, indicating intermittent migration between Europe and North America.

So, Europasaurus isn’t your average sauropod. Because it was restricted to an island environment, Europasaurus became very small. Even though it was related to some of the largest herbivores that ever existed, it still managed to be very small. It breaks yet another stereotype for sauropods: that they were all giants. Even the most homogenous groups are more diverse than previously thought, and further fossil evidence will show even more thrilling remains that help us understand a lot about sauropod diversity, and dinosaur diversity in general.

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Nigersaurus taqueti: Diverse Diplodocoids.

Size: 29.5 feet (9 meters) long.

Time Period: The Aptian or Albian Stage of the Early Cretaceous.

Locale: The Elrhaz Formation of Niger.
Name:
“Lizard from Niger.”

 Diplodocus is one of the most famous and interesting sauropods known. Though many of its relatives were morphologically similar to it, or even slightly different (in the case of Apatosaurus and co.), some were not. Other relatives of diplodocids didn’t bear a superficial resemblance to it, and these included the sail-backed dicraeosaurids like Amargasaurus (an animal that I ditched for Spinophorosaurus), as well as the rebbachisaurids. Nigersaurus is one of these creatures from this group.

 Though it was a common genus, Nigersaurus remained very much obscure until 2005, because of the construction of its bones, which were filled with air spaces. The fossil’s remains were subsequently highly disarticulated. In 2005, Paul Sereno and Jeffrey A. Wilson described the adaptions and phylogeny of Nigersaurus (some of this analysis is shown in the pictures above). It was only then that this animal and its kind became widely known and recognized as the oddity that it was.

 The animal had an unusually wide mouth shaped almost like the intake slot of a vacuum. This mouth took in food and chewed said food with a quantity of over a hundred very small teeth. This means that the animal’s teeth formed a tooth battery like the ones seen in hadrosaurs and ceratopsians. The fact that the rebbachisaurids possessed tooth batteries as well is very important in showing that the feeding habits of various kinds of sauropods were extremely diverse.

 Nigersaurus had as many as 500 or 600 teeth in its head. Not all of them were active, however. The animal had more than 50 columns of teeth lined up on the jaws, and CT scans showed up to nine replacement teeth stacked behind every single tooth, and Sereno’s studies show that one tooth wore out in about a month. Since the teeth were stacked up like Dixie cups, another one would immediately rise up to replace it. This efficient system ensured that Nigersaurus was always able to replace its teeth and eat without any pause. 

Additionally, studies of the inner ear show that the most common neck carriage for Nigersaurus was for the head and neck to point downward, indicating that the animal ate low-growing plants. It’s simply too bad that grass wasn’t a prevalent component of the flora during the Early Cretaceous, because Nigersaurus would be the perfect grazer if it lived today. Whatever the case, it’s clear that the animal grazed on low-growing vegetation, whether it was ferns or water-loving plants. The neck, like those of most Gondwanan sauropods, was actually shorter than that of most Laurasian sauropods. This may be a response to the different kinds of fauna found in Laurasia and Gondwana. Maybe it was just so the animal could better reach lower-growing plants, possibly like other Early Cretaceous diplodocoids. Additionally, Nigersaurus possessed a low spinal ridge on its back, which would have created a sort of skin sail that stretched across the neural spines, like some of the other dinosaurs in its environment, such as Spinosaurus and Ouranosaurus. 

Anyway, Nigersaurus would have come into competition with Ouranosaurus, the sail-backed (or possibly hump-backed a la All Yesterdays) advanced iguanodont that it shared its environment with. Since both most likely fed on the same food, it is possible that rebbachisaurids and low-browsing diplocoids outcompeted most of the ornithischian herbivores in their environments. Since rebbachisaurids lived in Arica, South America, and Europe, it would explain the tendency of sauropod prevalence in these areas. Maybe the opposite thing happened in Europe, where rebbachisaurids like Demandasaurus and Cathartesaura may have been outcompeted by the more successful iguanodonts and their quickly evolving descendants, the hadrosaurids.

 In conclusion, Nigersaurus represents one of the strangest, most interesting deviations from the ‘normal’ diplodocoid body type. It shows that sauropods may have fought their own battles over the most tantalizing of niches against the ornithopods, and they may have even won a few.

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Kosmoceratops & Company: Diversity and Ecology

There have been many recent discoveries in the world of dinosaurs that have been very groundbreaking. However, some of the most interesting creatures can be the ones that we expect. I have always expected that ceratopsians with weird horns would continue to be discovered, whether their horns stick up, curl down, protrude, or are reduced to facial bosses. In Utah, three remarkable ceratopsians have been discovered, and convince me that we may not have seen anything yet. They are all from the Kaiparowits Formation, and their age was placed as Late Campanian. All were herbivorous, and all were preyed on by Teratophoneus, the (also recently discovered) tyrannosaurid apex predator of the area. They are as follows:

Kosmoceratops richardsoni. This chasmosaurine is the most ornately adorned dinosaur known so far, and has multiple horns hanging over its frill, not to mention the standard brow and nose horns that are common in it and its relatives. This animal may not be evolutionarily pivotal, but it does tend to be interesting to look at. It most likely merits its own genus, because it doesn’t fit into any other species’ possible growth stages the way some other dubious ceratopsian genera seem to.

Utahceratops gettyi. After looking at this fantastically-frilled chasmosaurine creature, I began to have a lingering suspicion that it was related to Chasmosaurus, and it may have even been a member of that genus. It had a similar head to that of the former dinosaur, complete with the smaller brow horns typical of C. belli. I’m probably never going to make the leap from dinosaur enthusiast to consultant, but this is something that may need to be assessed. After reading some of Gregory Paul’s more recent work, I have realized just how complex the ceratopsians are to classify, and Utahceratops definitely needs a second look.

Nasutuceratops titusi. The only centrosaurine ceratopsian discovered from the Kaiparowits formation so far is quite the interesting specimen. It has impressive horns reminiscent of a longhorn cattle’s. The nature of these horns would be more befitting of a chasmosaurine ceratopsian, and I find it interesting that dinosaur such as this and Albertaceratops (both of whom are fairly early centrosaurines) have similar horns to their later relatives. This suggests that the two groups evolved these horns convergently. This genus has yet to be properly described, which is why Wikipedia yields no information about it as of right now.

What I find so interesting about these animals is that they managed to coexist in the same environment. They were all roughly the same size, and (to my knowledge) none of them exhibited very radically different teeth than their relatives did. It’s possible that their populations were equal in number and that they did eat all of the same things. However, as modern ecosystems tell us, related herbivores often develop different diets in order to discourage unwanted competition. It may have been the same for these horned dinosaurs.

So, while dinosaurs like these may be mere eye candy for some, I find their shared presence intriguing and evidence of complex ecosystems like those we see among mammals today. It is yet another interesting window into the world of the dinosaurs.

Edmontosaurus’s cock’s comb and the Soft-Tissue Debate

In a war waged by All Yesterdays and many ardent fans of paleoart and prehistory, it’s being boldly stated that the presence of soft-tissue display organs and integument in dinosaurs was far more prevalent than previously thought. Gone are the shrink-wrapped dinosaurs of yester-year, and in their place are flamboyant dinosaurs covered in feathers, fat, and fiery colors. Recently, these depictions have gained a lot of traction, and a new discovery in paleontology makes the idea that a skeleton doesn’t present the complete image of an animal even more apparent to the few nay-sayers of the paleontology community that are left. 

This finding concerns Edmontosaurus regalis. This highly successful hadrosaur was an extremely common sight near the end of the Mesozoic era, and creatures like it roamed from Mexico to Mongolia at the time. I wouldn’t ordinarily do a post on it (though I did to a post on its relative Shantungosaurus) because, well… it just looks kind of drab. It’s one of the crestless hadrosaurs, animals far less cool and flamboyant than Parasaurolophus and its posse. Or was it?

This compelling new find suggests that Edmontosaurus did have enough street cred to sport a crest like its more hip relatives. Unearthed from the Red Willow river in Canada, the new specimen preserves the remains of a crest made of skin. It wasn’t hollow or made of bone, and thus cannot have served as the kind of sound system that the aforementioned Parasaurolophus may have used with its own crest. Edmontosaurus’s skull adornment has been likened to the crest of a rooster, and may have been used for sexual signaling in a similar fashion. 

I think it’s kind of ridiculous that this is considered such a big deal, though. It seems inevitable to me now that we’d find these sorts of display structures in dinosaurs, which are known to implement ornaments like frills, horns and crests in sexual selection. We all knew that it was going to happen sometime, so it just doesn’t seem to be that huge of a deal to me.

Still, it changes Edmontosaurus’s overall look greatly. The crest does a stupendous job of demonstrating that, no matter how much we may think we know a dinosaur based on skeletal remains, we can never truly know it the way its contemporaries did. And with that, I end this belated update.

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Gigantspinosaurus sichuanensis: Extreme Body Armor.

Size: 14 feet (4.2 meters) long.
Time Period: The Oxfordian Stage of the Late Jurassic.

Locale: The Shaximao Formation of China, a part of the Dashanpu Formation.

Name: "Giant-spined lizard from Sichuan, China."

Stegosaurs, as I’ve mentioned before, get more press than their more successful relatives despite the fact that they couldn’t keep up with said relatives (see my post on Dravidosaurus). The most distinctive member of the Stegosauria is Stegosaurus itself, who actually didn’t possess some of the defining features of its relatives, such as spines on the back and shoulders. This leads some to believe that all stegosaurs possessed plates like those of Stegosaurus, but guess what? They’re wrong.

Sporting some particularly fine spines was Gigantspinosaurus from the Late Jurassic of China. They, along with the animal’s intriguing taxonomical history, are the reason that this post even came to be.

First comes the history of the fossils themselves. The fossils of Gigantspinosaurus were discovered in 1985 and described soon after in 1986. The describers actually mistook the animal for the contemporaneous species Tuojiangosaurus. Until 2006, Gigantspinosaurus was considered to be a nomen nudum or ‘naked name’ in the Western world. Then, it was disclosed that there was a sufficient description of the animal’s remains in the abstract written by the describers of the animal. Images of the animal had already appeared in sources prior to ’06, when Tracy Ford published an article on reconstructing the animal, considering Gigantspinosaurus to be a perfectly valid taxon. The animal was concluded to be a valid taxon that same year but wasn’t redescribed fully.

Phylogenetic analyses place Gigantspinosaurus as the basalmost known member of the Stegosauria. Given the scanty fossil record of early representatives of this group, we don’t know how the hell the animal’s distinctive spines evolved and may never know. Some subsequent analyses placed it in Huayangasauridae, a primitive branch of the group. I’m not too sure myself as to the affinities of the animal, but I think it may be likely that it was a sort of stepping stone between basal and more derived stegosaurs.

Now, I could talk about nomenclature and phylogeny some more, but I’m sure everybody wants to hear about Gigantspinosaurus’s huge macho spines, which gave it a really distinctive appearance. Anyway, Gigantspinosaurus  had small dorsal plates for its size, but greatly enlarged shoulder spines that were two times the length of the shoulder blades that they rested on by way of large flat bases. The first reconstructions of the animal show downward-pointing spines, which was later proven to be an error by the aforementioned Tracy Ford, who suggested that these reconstructions had incorrectly attached the animals shoulder spines upside-down. Subsequent reconstructions (Including Xing Lida’s, shown above this post) showed it with spines that extended upwards and ended higher than the top of the animal’s back, but not higher than its distinctive plates. In addition, the animal was found with skin impressions, described by the aforementioned Xing Lida in 2008.

So why were these spines needed? Were they for attracting mates, warding off predators, or for something else entirely? They certainly drew public attention to Gigantspinosaurus, but the questions remain unanswered. It seems ironic that the spines of the animal, its most iconic feature, have not been found to have any discernible use so far! Macho spines or not, this animal is very cool.

2013 News Tidbits

I am going to release one more post after this before going on a two-week hiatus, because there are some new 2013 dinosaurs on the horizon. They are

Dongyangopelta yangyanensis, the second nodosaurid known from China and Asia in general. It is known from the early Cenomanian stage of what is called the “medial” Cretaceous period, and hails from a formation known as the Chaochuan formation. Unfortunately, there’s no information about it on the internet. Though this is an interesting discovery, I’m still keeping my fingers crossed for an Asian Late Cretaceous nodosaurid that resembles Edmontonia.

and

Gannansaurus sinensis,another Chinese dinosaur. This time, it’s a sauropod that closely resembles the titanosauriform Euhelopus. However, it’s from a little later in time than that animal, hailing from the Nanxiong Formation. Its home was shared with a few different dinosaurs, such as Microhadrosaurus and Banji. Overall, Nanxiong Formation fauna resemble the animals that have been found in the famous Nemegt formation. 

Don’t get too excited about these discoveries yet. Dongyangopelta was named from a femur, a presacral rod, and an ilium, and Gannansaurus was named from a single dorsal vertebra and a mid-caudal vertebra. However, Dongyangopelta does interest me, and I look forward to seeing more dinosaurs from China this year.

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