You all like dinosaurs, right? Have some theropod wrists. I’m writing a paper on therizinosaur phylogeny and wrist characters are kind of a big deal, but when I say ‘typical maniraptoran wrist’ my ecology class just looks at me blankly. Pictures!
Yep, the big paleo news this weekend was the official announcement of some new fossil material for this particular dinosaur.
Deinocheirus (“terrible hand”) came from the Late Cretaceous of the Gobi desert, about 70 million years ago. Originally discovered in 1965, the only bones known were a set of enormous arms and a few scattered ribs and vertebrae. It was a long-standing mystery for paleontologists. Was it a megalosaur? A carnosaur? Some new type of theropod altogether? A predator or a herbivore?
Some more recent studies suggested it might be an ornithomimosaur, albeit a fairly primitive one based on the arm anatomy. With the two new specimens that have been found, we’ve now got confirmation of that placement — Deinocheirus really was an enormous “ostrich mimic”, the largest known for that group.
This is the famous Velociraptor mongoliensis in its native late Cretaceous Gobi Desert. Velociraptor was a small dromaeosaur, or raptor dinosaur, and contrary to its most famous depictions was almost certainly feathered from head to tail. This is no longer based merely on phylogenic evidence, either - as of 2007, reanalysis of the fossil has shown that its posterior forearm contains quite obvious quill knobs.
Velociraptor surely went after larger prey like Protoceratops at least occasionally, as we have fossil evidence that it certainly did so. However, like many modern mid-sized carnivores, its diet probably consisted of a large proportion of much smaller animals, which it may have ambushed or sniffed out of crevices. I imagine such a predation event would have been rather felid in nature, wherein the animal displayed a curious mixture of predatory grace and pure silly ridiculousness as it bounced and flailed after a frantic prey animal. In this case the prey in question is Zalambdalestes, a small shrewlike eutherian from the Djadochta Formation of Inner Mongolia.
How Birds Evolved From Small Meat-Eating Dinosaurs
by Joel N. Shurkin, ISNS Contributor
Some time, perhaps 150 million years ago, small-feathered dinosaurs called maniraptorans began to develop longer arms and shorter hind legs, kick- starting the evolutionary process to becoming the birds we see today.
All of today’s 10,000 bird species, from the hummingbird to the condor, evolved from that simultaneous physiological change, posits a paper published in the journal Evolution by Hans Larsson, a macroevolution researcher at McGill in University’s Redpath Museum in Montreal, and Alexander Dececchin, a graduate student now at the University of South Dakota in Vermillion. Their research was based on dozens of data sets from fossil records.
Before the transformation began, the relationship between the size of the maniraptorans’ limbs and body had been steady through millions of years, they said. Not only that, the species were surviving just fine on the ground, not in trees, as earlier theories about maniraptorans suggested…
Khaan mckennai was an oviraptorid from the Late Cretaceous of Mongolia, about 75 million years ago. About 1.2m (4ft) long, it was initially identified as belonging to the genus “Ingenia" before being assigned its own unique name in 2001.
Oviraptorids were members of the maniraptorans, closely related to birds and “raptors”. They were initially considered to be specialized egg-eaters due to an Oviraptor fossil discovered on top of a nest which was thought to belong to the ceratopsian Protoceratops. (Hence the name “Oviraptor”, meaning “egg thief”.) Later specimens found during the 1990s showed oviraptorids clearly brooding on top of nests, however, and the original eggs turned out to have belonged to the Oviraptor the whole time.
Here is my rendition of Eosinopteryx brevipenna, the new troodontid described last week in Nature Communications. This tiny feathery, from the Late Jurassic Tiaojishan formation of Liaoning, China, differs from other basal troodontids in that it lacked the long feathers on the metatarsals and pes that typifies related animals, such as Anchiornis. It also had much shorter footclaws than related species, and this together with the lack of “legwings” indicates it was very likely a terrestrial bird. The animal is also a bit unusual in that its tail is rather short and lacks any sign of retrices, which gives it a bit unusual and somehow more “primitive” appearance than its relatives.
Here, the little fellow perches atop a mossy stump, possibly the highest vantage point it was able to manage. The paper makes no mention of whether the ungual on the second digit of the foot could be retracted, but the fossil’s second pedal claw is clearly larger than the other claws on the foot, so it’s possible it was used to aid in balance as well as predation.
….still kind of doing these and yes, I skipped day 4 because that comes under a different day. Anyway! This is supposed to be archaeopteryx doing that wing stretchy pose birds do… I say supposed to be, since as always I’m not claiming scientific accuracy here. (also aware that at least some of their feathers were supposed to be black but… it ended up being… not black <.<)
This one looks kind of strange because I was experimenting with a different graphics program and colouring technique. It sort of didn’t work, sadly. So here’s the mostly flat coloured version instead.
Xixiasaurus henanensis (pronounced “shee-shah-saurus”) was a troodontid from the Late Cretaceous of China, about 83 million years ago. Its size is difficult to estimate, based only on the front portion of a skull, but it may have been somewhere in the region of 1.5m long (5ft).
Troodontids were very bird-like dinosaurs, closely related to both the dromaeosaurs and true birds. They had long legs and appear to have been fast runners, and possessed “sickle claws” on their feet — although not as large or curved as those in their dromaeosaur relatives. Large eyes and asymmetrical ears suggest that they may have been specialized for nocturnal hunting in a manner similar to modern owls, using a keen sense of directional hearing to locate small prey.
They also had some of the biggest brains in relation to body size of all dinosaurs, roughly comparable to those of modern flightless birds. This has led to speculation about their intelligence, and the creation of the (rather problematic) “dinosauroid" thought experiment in the 1980s.
Here’s my submission to Love in the Time of Chasmosaurs' version of the “All Yesterdays” contest. This version of the contest is differentiated from the original by requiring the artist to illustrate the speculative behavior in a style different from their usual, with a specific emphasis on straying from the hyper-detailed, realistic style that most paleoartists seem to be trying to capture these days. I tried a sort of cell-shaded, pseudo-vector type of look for mine, which I'm sure most of you will notice is very different from my usual fare.
Anyway, this is a little different from most entries to this contest in that while it’s speculative, it is something that I genuinely believe is the case (that Microraptor was an omnivore), and I think it’s perfectly possible that one of the ~300 undescribed specimens of this animal may preserve plant matter gut contents. Hard to say. In any case, I think that Microraptor has certain features that are consistent with omnivory in maniraptorans, including having somewhat unusual dentition by dromaeosaur standards.
Here I’ve depicted it munching on a tasty cycad fruit.
I intend to do a more in-depth blog post exploring this concept sometime in the coming weeks. I also hope that my watchers aren’t sick of me drawing Microraptors yet… there will be more to come.
Falcarius utahensis was an early therizinosaur from the Early Cretaceous of Utah in the United States, living about 126 million years ago. It grew up to 4m (13ft) long and has been estimated to weigh around 100kg (220lbs).
Therizinosaurs were a branch of the maniraptoran theropod dinosaurs — a group including the more popular “raptors” and modern birds — but unlike their more predatory relatives they were adapted for herbivory. Falcarius was a transitional form between typical theropods and the later, more derived therizinosaurs.
Two different interpretations of the same dinosaur. Also featuring a slightly mangled small pterosaur.
B is for Balaur
Balaur bondoc (a very fun name to say out loud, meaning “stocky dragon”) was an unusual little dromaeosaur from the Late Cretaceous of Romania, living about 70 million years ago. At about 2m (6’6”) long, it was roughly the same size as the closely-related Velociraptor.
It was more heavy-set and muscular than other “raptors”, and only had two functional fingers on each hand. The first toes on its feet, usually vestigial in other dromaeosaurs, were modified into a second pair of retractable sickle claws. Being built much more for strength than speed, it may have used its powerful claws to pin prey to the ground and then hung on until the victim was exhausted, flapping its feathered arms to keep its balance.
Balaur's unique anatomy seems to have come about due to the species being isolated on an offshore island archipelago. Several other odd fossils are known from the same area, including dwarf sauropods and one of the largest pterosaurs ever.
But there’s also a completely different possible interpretation of Balaur. Its unusually swept-back pelvic bones and four-toed feet have been compared to similar adaptations in the therizinosaurs, where the pelvis made room for large plant-digesting intestines and the extra toe was used for weight-bearing rather than as a weapon. Combined with the reduced usefulness of Balaur's hands in predation, there's the suggestion that it might have been an omnivore or herbivore.
While a fascinating idea, there’s no conclusive evidence for that — the one known specimen of Balaur is rather incomplete and entirely lacks any skull or tooth material. Without a head (or a holy-grail-esque discovery of gut contents) it’s impossible to know for sure what this particular dinosaur was up to.