sauropodomorphs

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I’ve seen this chart floating around on my dash, and it occurred to me that I never posted the original version. So here is my and Jon‘s Dinosaur Classification Chart, in a hopefully Tumblr-palatable format.

Click here to see the moderately large version at DA.

This is a much simpler examination of dinosaur relationships than most of my watchers would probably find useful. Most of you will know that theropods are broken up into tetanurans and ceratosaurs, and that birds are nested within coelurosaurs, and that there are many internal divisions within sauropods and ornithiscians as well. But this chart is intended to be more of a quick, concise reference for laypeople, teachers, children, or whoever might have a passing interest in dinosaurs. My hope is that anyone who wants to quickly figure out what major group any given dinosaur falls into can glance at this chart and know immediately. 

This was a collaboration between myself and Jon - I did the illustrations, and he did all of the layout and text. To see this chart in full resolution, please consider buying a poster in my Zazzle shop.

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Carnegie Museum - Part 1

The first thing that greets visitors on the way to the Carnegie Museum of Natural History is an Apatosaurus statue—life-size, I believe. It certainly whets the appetite for all the nice dinosaur mounts in the exhibition hall. Just inside, there’s a fossil prep lab open for the public to see, including this little line of lambeosaurine skulls. Just ahead of that, a Herrerasaurus mount marks the entrance to the Hall of Dinosaurs. My inner ten-year-old may have taken over at about this juncture.

The phytosaur is a Redondasaurus, and it seems much bigger in person. I’d hate to find myself caught in a Triassic swamp with something like that. A few steps down is a Camarasaurus cast, mirroring in situ skeletons out west in Dinosaur National Monument. Lastly, on the cusp of the next, largest part of the hall, a dryosaur fleeing desperately from a Ceratosaurus because this is all dryosaurs ever did.

Next post, the Jurassic hall, including the Carnegie Diplodocus.

Today I am giving myself a break before tomorrow! 

What’s tomorrow, you ask? 

THE START OF THE SAUROPODOMORPHS

WE DID IT GUYS! 

WE DID THE THEROPODS (EXCLUDING MOST OF AVIALAE, SOME DUBIOUS TAXA WHICH I MIGHT DO AT SOME OTHER POINT I DUNNO, AND NEWLY DISCOVERED DINOSAURS THAT I SHOVED IN LATER IN MY SCHEDULE).

LETS HAVE SOME FUN WITH THE OTHER TYPE OF SAURISCHIANS NOW!

WOOOO!

WE DID IT!  

A dinosaur with a rather unfortunate name: Pantydraco.

Giggle all you want. I’ll wait.

Named for the location of its discovery, the Pant-y-ffynnon Quarry in Wales, this early sauropodomorph lived at the very end of the Triassic about 205-201 million years ago. It’s only known from a partial juvenile skeleton – probably around 1.5m long (4′11″) in life – but the full adult size is unknown.

Unlike the later quadrupedal plant-eating sauropods, Pantydraco was bipedal and may have been omnivorous. And while we know some of its more famous giant relatives were definitely scaly-skinned, with the increasing evidence for fuzz being ancestral to all dinosaurs it’s not too much of a stretch to think these basal ‘prosauropods’ were still fluffy, too.

(Also: check out this post for a good summary of ‘prosauropod’ anatomy.)

AMARGASAURUS
“La Amarga lizard”
Early Cretacous, 129.4-122.46 million years ago

Amargasaurus was not large compared to its sauropod relatives; it grew to only about 33 feet in length. It stood out, however, because of its double row of long vertebral spines. Some experts have interpreted these spines as supporting sails, much like Spinosaurus, and others have suggested they were for thermoregulation. The current consensus is that Amargasaurus clattered the spines together as a sound display, making it the annoying toddler of the sauropod world.

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Carnegie Museum - Part 2

The Jurassic hall is the oldest part of CMNH’s dinosaur display, the huge Diplodocus carnegii being the museum’s first dinosaur. This part of the hall has been updated with newer fossils since then, offering an impressive collection of Morrison fauna (and others). Across from the Diplodocus is its smaller cousin Apatosaurus, plus a juvenile underneath. Nipping at its tail is a possibly unwise Allosaurus.

Around the edge with the mural one finds the ornithischians represented as well, with Stegosaurus and Uteodon. Above the latter is a small mounted pterosaur, probably Pterodactylus by the looks of it.

Speaking of whom, there is a cast of the original Pterodactylus antiquus specimen nearby, along with that of the first full Archaeopteryx from Solnhofen.

Around the corner, one crosses over into the Cretaceous and, conveniently, a separate post.

Plateosaurus engelhardti was a large(ish - okay, big cow-sized) sauropodomorph from the Triassic of Europe. This painting’s mostly about the fungi, though. This a a surprisingly complex Photoshop painting: I went  crazy with the layers.

Hmm, it’s been a while since my last new work, I’m going through a un-motivated patch. Seems I can’t keep producing a new thing every few days forever.

Saturnalia tupiniquim was an early, basal sauropodomorph dinosaur found in Rio Grande do Sul, southern Brazil. It lived during the Late Triassic (Carnian).

It is known from three partial skeletons lacking skulls, except for an impression of a dentary with teeth. Saturnalia was probably an omnivore with an estimated length of around 1,5 meters (5 ft).

It would have used a bipedal gait probably to escape from predators, but also for active hunting of small prey, when relatively fast locomotion was advantageous. However, it was probably not an obligatory biped. During a slower pace, perhaps while moving through areas with vegetation that could be eaten it is likely it walked on all fours.

This restoration is based on the likelihood that proto-feathers were present in basal dinosaurs.

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Overly Simplified Archosauria Cladogram
✧・゚:* \(◕‿◕✿)/ *:・゚✧

Featuring notable groups for easy identification, and a reason for this nerd to point out that Pterosaurs are not Dinosaurs. They are better than Dinosaurs and I’m not sorry to say this.

As an artist I am aware that it’s not easy for some people to understand the relationship between things from Wikipedia when all we see is latin names (which luckily I grew up with). It’s helpful to have pages with descriptive icons attached next to the phylogenetic tree, but we all know it takes time to edit all those pages one by one and seriously, who has time for that.

So I made this quick chart to help my non paleonerd friends to understand the basics. One day, when I’m done with all 81 Sauropsid daily drawings, I’ll make one big sheet to rule them all. So Paleotumblr, if you could help me to come up with a consistent list of the clades’ common names (that non-nerds could understand), I’d be grateful.

I know there are plenty of Theropodnerds following me but I can’t fit a ton of those guys here, so don’t complain about it okay.

- - -

Will Art for Science · Find me elsewhere

CAMARASAURUS
“Chambered lizard”
Late Jurassic, 155-145 million years ago

Camarasaurus had a domed skull like Brachiosaurus, but the “chambers” referred to in its name are actually in its backbone – hollow vertebrae housed air sacs that reduced weight and helped such a large animal move. Its strong teeth would have been excellent for grinding tough vegetation, allowing it to occupy an ecological niche separate from its slender-toothed contemporary, Diplodocus. In fact, Camarasaurus was the most common sauropod of the Jurassic, and familiarity breeds contempt.

nature.com
A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot
Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole.

Notocolossus gonzalezparejasi, a new large titanosaur from the Coniacian/Santonian (LK) of Argentina!

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Tapuiasaurus macedoi: The Skulls of the Titans.

Size: About 40 feet (12 meters) long

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

Locale:  The Quirico Formation of Brazil.

Name: The generic name means “Tapuia lizard,” from “Tapuia,” a generic name used to designate tribes from the inner regions of Brazil. The specific name honors the discoverer of the fossils, Ubirajara Alves Macedo.

The titanosaurs were debatably the most successful group of sauropods. As one of the only groups to make it to the Early Cretaceous, they became the only kinds of sauropods found anywhere on earth by the Late Cretaceous Period. Since they’re so successful, it’s surprising that we have so little information about their skulls, the parts of their anatomy which would have allowed them to eat, survive, and become as successful as they were in the first place.

Before the discovery of Tapuiasaurus macedoi, only two titanosaur skulls were even known; that of Rapetosaurus from the Maevarano Formation of Madagascar and that of Nemegtosaurus from the Nemegt Formation of Mongolia. Both are lithostrotian titanosaurs and both were derived members of the Titanosauria that lived close to the end of the dinosaurs. That’s why the find of Tapuiasaurus is important. Not only is it (rather surprisingly) the only titanosaur skull known from South America, the place where most titanosaurs are found, but (more importantly) it is from the Early Cretaceous rather than the Latest Late Cretaceous.

Before I talk about Tapuiasaurus, however, I have to talk about titanosaur skulls in general. Little is known about how they evolved, but they showed strange convergences with the skulls of the unrelated diplodocids, in that both possess posteriorly displaced nares, thin-crowned cylindrical teeth that were mostly in the front of the snout, and forward leaning quadrates. In fact, many early books will argue that Saltasaurus, Alamosaurus, and all titanosaurs in general were diplodocoids that survived into the later Cretaceous. Of course, further studies suggest that they were macronarians that were most closely related to the brachiosaurids.

Anyway, it turns out that the skull of Tapuiasaurus shows that it was actually a very derived representative of its group. The fact that it was found in the Aptian Stage of the Early Cretaceous and that its skull looked very similar to that of Rapetosaurus means that the basic skull structure of the titanosaurs probably remained largely the same throughout their evolutionary history. This entails the existence of 30 million year-long ghost lineages of advanced titanosaurians, whose very early diversification and dispersal may explain the fact that they were present and very similar in appearance even though species were all generally isolated from one another by the time animals like Rapetosaurus and Nemegtosaurus walked the earth. These animals probably also retained their body type for so long simply because it was a successful evolutionary innovation. It may have even been a reason that they outlived the diplodocoids, who had become so specialized that they couldn’t cope with the change in climate during the Cretaceous while the titanosaurs survived. The groups probably didn’t compete, and the titanosaurs most likely gained their body type as a result of an opportunistic radiation.

In conclusion, Tapuiasaurus is a very important find because it is accompanied by a skull, a very rare thing for a sauropod to be found with. It’s always a good thing to find a sauropod skull, because skulls like that of Tapuiasaurus often have a very big story to tell.

Shunosaurus lii is one of the best anatomically known of all sauropod dinosaurs, represented by a large number of fossils including several near-complete skeletons. Living during the Middle Jurassic of China (~170 mya), it reached lengths of about 9.5m (31′2″) – and while its evolutionary relationships are somewhat disputed, it may have been related to other Chinese genera such as Mamenchisaurus and Omeisaurus.

Unusually for a sauropod, it had a proportionally short neck, suggesting it specialized in a different type of diet than its longer-necked relatives. Even weirder, it was also the first sauropod found to have a spike-tipped club at the tip of its tail, which may have served a defensive purpose convergently similar to the tail weapons seen in ankylosaurs and stegosaurs.

Pangender Panphagia experiences a wide variety of genders, and their identity is comprised of many different gender expressions that can go beyond the current knowledge of genders.  This sauropodomorph knows that their desire to include aspects of any (or all) genders into their life is limited only to their own personal life experience within their own particular culture - you are the only person with the right to name and describe your gender, and your usage of the term pangender should never be viewed as cultural appropriation, if you use it to describe your feelings toward that very personal part of yourself.  

Although it did not resemble the massive, long-necked sauropods of the Jurassic and Cretaceous periods, Panphagia is in fact the earliest known ancestor of the group - and one of the earliest known dinosaurs overall.  

“Nurosaurus” qaganensis: China’s nomen nudum.

Size: About 80 feet (24.3 meters) long.

Time Period: The Hauterivian stage of the Early Cretaceous period.

Locale: The Gobi desert of eastern Asia.

Name: The generic name means “lizard from Nur.”

Everybody knows about Camarasaurus, an animal that’s just about the most generic sauropod in the Morrison Formation. Though it is kind of an important and very common animal, it’s just not very interesting compared to contemporaries such as Suuwassea, Supersaurus, or even the fairly generic Brachiosaurus. Here, I talk about a potential relative of Camarasaurus that isn’t the familiar animal that its American pal is. In fact, this relative isn’t even a formally described taxon.

“Nurosaurus” was discovered a while ago, and is now known from a partial skeleton that has been on tour very often. The problem with this exposure to crowds at traveling exhibitions is that this animal has been presented with a number of misspelled names. Though “Nurosaurus qaganensis” is the proposed binomial name of the taxa, “Nuoerosaurus chaganensis” is just one of the many misspellings that has been seen. The source of this confusion is mainly that the taxon hasn’t been described in the right way yet, so the name isn’t final.

“Nurosaurus” was one of the largest dinosaurs ever to live in China, ranking among such huge oriental sauropods as Mamenchisaurus and Ruyangosaurus. The interesting thing is that it was related to the smaller Camarasaurus, a primitive macronarian. These animals had similar head and body structures, and their back vertebrae were alike in that their neural spines were similarly split. The fact that “Nurosaurus” was a lot larger than Camarasaurus may have to do with it having been a more dominant herbivore in its ecosystem than its American relative.

The presence of a camarasaurid in China as opposed to North America may hint that a wider distribution of these dinosaurs existed than initially thought. The number of sauropod radiations in the middle to late Jurassic period probably was larger than we know, and the radiation of camarasaurids would be in a similar time-frame to that of animals like Spinophorosaurus or Dicraeosaurus.

Though “Nurosaurus” isn’t a very well-known animal culturally or scientifically, more research about this animal could tell us some interesting things about the phylogeny of camarasaurids. Even though we may consider Camarasaurus generic and boring, the overall story of its family heritage may be more complex than meet the eye.

plosone.org
PLOS ONE: Evolution of High Tooth Replacement Rates in Sauropod Dinosaurs

External image

By Michael D. D’Emic, John A. Whitlock equal contributor, Kathlyn M. Smith, Daniel C. Fisher, Jeffrey A. Wilson

Abstract

Background

Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates.

Methodology/Principal Findings

We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days). Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section.

Conclusions/Significance

Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size), and derived titanosaurs and diplodocoids independently evolved the highest known tooth replacement rates among archosaurs.

What on Earth is this!?!??!!?

Chilesaurus diegosuarezi from the Late Jurassic of Chile has functionally two-fingered hands, four toes on the floor, leaf-shaped teeth, and reversed pubes, all characteristics related to reduction of running and predatory ability. However, despite sharing characteristics with ornithischians and sauropodomorphs, it is a tetanuran theropod! As a first-order approximation, it’s like someone took a therizinosaur and gave it tyrannosaurid forelimbs, yet it is not closely related to either. Non-hypercarnivorous forms abound among the maniraptoriform coelurosaurs, but this critter (along with the ceratosaur Limusaurus) appears to represent an independent derivation of theropod herbivory. Perhaps it is a good time to take a look at Eshanosaurus again.

I wonder whether anything will top this in dinosaur paleontology this year… We’re not halfway through yet.

MAMENCHISAURUS
“Mamenchi lizard”
Late Jurassic, 160-145 million years ago

If sauropods are known for their long necks, Mamenchisaurus is the poster child. The largest species (M. sinocanadorum) reached an estimated 115 feet, and half that length was neck! These prodigious proportions would have been useful for reaching the choicest vegetation from a single spot and, obviously, compensating. Maybe overcompensating. Calm down, Mamenchisaurus.