Originally known only from a foot, with scarce remains found since, Elmisaurus rarus means “Rare Foot Sole Lizard.” Even today, Elmisaurus fossils are highly fragmentary, as are most Caenagnathid remains, and consist mostly of foot and hand bones. However, if the fossils of Nomingia gobiensis can actually be attributed to Elmisaurus, which they may be, we might have a bigger picture of the animal. Elmisaurus has been the subject of but one study so far, where 23 foot bones from various specimens were studied for signs of stress fracture, and none were found. This animal was probably lightly built and not using its feet for strenuous activities. Rather, like other oviraptorosaurs, it would have relied on a sharp beak and strong bite force, lending to either herbivory of tough plant material or omnivory of both plants and small creatures.
Found in Late Cretaceous Mongolia, Elmisaurus rarus would have lived in the arid canyons of the Nemegt Formation. This environment was not entirely desert like the older Barun Goyot and Djadochta Formations, but also filled with thickly wooded forests of tall conifer trees and shallow lakes. It would have shared this environment with other oviraptorosaurs like Rinchenia, Nemegtomaia, and Avimimus. It would have also lived alongside troodontids like Tochisaurus and would have had to look out for Tyrannosaurs like Bagaraatan and Tarbosaurus. Hadrosaurs like Barsboldia and Saurolophus, the pachycephalosaurs Homalocephale and Prenocephale, sauropods like Nemegtosaurus, and the crocodylomorph Paralligator also lived here, as well as turtles, frogs, and small mammals.
If Nomingia is actually Elmisaurus, then it would have also lived alongside ornithomimosaurs like Anserimimus, Gallimimus, and Deinocheirus, the dromaeosaur Adasaurus, the bird Brodavis, alvarezsaurs like Mononykus, troodontids like Zanabazar, and Therizinosaurus in the Bügiin Tsav locality of the Nemegt Formation.
This art may be used for educational purposes, with credit, but please contact me first for permission before using my art. I would like to know where and how it is being used. If you don’t have something to add that was not already addressed in this caption, please do not repost this art. Thank you!
The newly discovered Caenagnathid Oviraptor-line dinosaur called Eoneophron infernalis (Dawn Neophron of hell). This emu sized theropod lived in the upper Cretaceous Hell Creek formation in South Dakota.
It was described as a new species from remains that were previously attributed to another Caenagnathid species called Anzu wyliei. The paper that described it, Atkins-Weltman et al. 2024, recovered it as closely related not to Anzu but another Caenagnathid called Elmisaurus.
chirostenotes pergracilis - caenagnathid - late cretaceous
this fluttery chirostenotes is accompanied by her (barely visible and Only Ten Pixel Wide) lovely little siblings tonight! named for their oddly narrow hands and one pointed, straight claw, this oviraptorosaur was thought to have used its talons for crevasse probing like modern day eye-eye. the representation here has feathers (that other caenag that wouldn't have allowed for it to do as such, sadly!
Anzu wyliei for Theropod Tuesday! Anzu is a caenagnathid (pronounced SEE-neg-NAY-thid) oviraptorosaur, meaning that it’s in the same general clade (group) of theropods (Oviraptorosauria) as Oviraptor. Caenagnathids, however, are a distinctive group within Oviraptorosauria, although much more poorly known than their “cousins,” the oviraptorids. Both lived in the Late Cretaceous epoch, and both are known from eastern Asia (Mongolia and China) and western North America (U.S. and Canada), but the oviraptorids seem more common and diverse in Asia while the caenagnathids are more common and diverse in North America. Anzu is the best known caenagnathid, and the first decently complete specimen from North America: between the known specimens, most of the skeleton is represented. It’s also one of the youngest oviraptorosaurs known anywhere: it comes from the latest Cretaceous Hell Creek Formation of North and South Dakota. The name Anzu is also the name of a feathered demon in ancient Mesopotamian cultures--the “feathered” aspect is particularly apt because oviraptorosaurs are known to have been feathered in life (see the painting on the wall behind the skeleton for a life restoration). The species name wyliei honors donors to the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, where the two most complete specimens, and this restored skeletal mount, reside. If you’re curious about the (ahem) proverbial meat and bones of this animal, the paper describing it is available free online at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092022 .
By the way, anyone else is also welcome to jump in with their own Theropod Tuesday photos...and remember, “theropod” includes birds!
Now that I’ve introduced the major groups of Oviraptorosaurs (oviraptorids, caenognathids, and outliers), we can begin to talk about their diversity. And we simply must begin with the largest oviraptorosaur: the truly gigantic caenognathid Gigantoraptor erlianensis.
Gigantoraptor was 8 metres (26 ft) long and weighed around 2 metric tons. Unusual for giant theropods, it also had long limbs, with both its tibia and femur measuring over 1 m (3.3 ft) long. Giant ovoraptorosaurian eggs have been found that were likely laid by Gigantoraptor or similar, yet unknown giant caenognathids. These eggs were placed in a ring around their nest, with no eggs in the center, likely to mimimize the chance of the parents crushing their own eggs under their weight. Gigantoraptor’s toothless, shearing beak indicates a herbivorous or omnivorous diet, similar to other oviraptorosaurs, however it could have also engaged in carnivory occasionally. And who would stop it?
Living in the Iren Dabasu Formation of Late Cretaceous Mongolia, Gigantoraptor was one of the largest dinosaurs in its humid, floodplain, river valley habitat. The largest predator (that has been found so far) was the tyrannosauroid Alectrosaurus, a 5 to 6 meter (16 to 20 ft) long pursuit predator that was probably about as tall as a human. If Alectrosaurus had any hope of catching a Gigantoraptor, it would have had to hunt in a group and target young and weak individuals. But there were plenty of other species they could have hunted, most of them far easier prey than Gigantoraptor. These could have included the ornithopods Bactrosaurus and Gilmoreosaurus and the speedy ornithomimosaur Archaeornithomimus. Other, smaller, oviraptorosaurs lived alongside Gigantoraptor, including the caenognathid Caenagnathasia and indeterminate avimimids. The therizinosauroids Erliansaurus and Neimongosaurus would have also shared the habitat. The only thing larger than Gigantoraptor in the Iren Dabasu Formation was the 9 meter (30 ft) long titanosaur Sonidosaurus.
While Gigantoraptor is the largest oviraptorosaur I’ll be covering, other giant species did exist. Giant oviraptorosaur nests and eggs have been found in multiple formations, including within North America, but the remains of adults have yet to be found…
This art may be used for educational purposes, with credit, but please contact me first for permission before using my art. I would like to know where and how it is being used. If you don’t have something to add that was not already addressed in this caption, please do not repost this art. Thank you!
The gracile caenagnathids are notorious for fossilizing badly, and as such Nomingia gobiensis is only known from its spine, upper legs, and tail (which is honestly more than most other caenagnathids). However, its tail represents a significant discovery for oviraptorosaurs. Nomingia had five fused vertebrae at the tip of its tail, a structure similar to the pygostyle of birds, that would have supported a fan of tail feathers. When Nomingia was found in 1994 and described in 2000, this feature was thought to be unique to birds. And while we have evidence of tail fans in other oviraptorosaurs, pygostyles themselves are rare. It’s unknown why Nomingia would have needed this, as it was certainly too big for flying. Perhaps, like Khaan’s tail fan, it was used for display, and the structure would have allowed it to have a sturdier, larger, more “sexy” tail fan.
As of 2021, it has been suggested that Nomingia may actually be Elmisaurus, but further study is needed to confirm this. Since caenagnathid fossils tend to be so fragmentary, this may take some time.
Hailing from the Bügiin Tsav and Nemegt localities of Mongolia’s Late Cretaceous Nemegt Formation, Nomingia would have lived alongside Avimimus nemegtensis in this seasonally arid environment characterized by cliffs, shallow lakes, and patches of conifer forests. If not Elmisaurus itself, it would have lived alongside it as well as the oviraptorids Nemegtomaia in the Nemegt and Oksoso in the Bügiin Tsav. There were of course other dinosaurs here, including Therizinosaurus, the troodontid Tochisaurus, the tyrannosaur Bagaraatan, the sauropod Nemegtosaurus, the hadrosaur Barsboldia, and the pachycephalosaur Homalocephale in the Nemegt.
In the Bügiin Tsav, Nomingia would have lived alongside the troodontid Zanabazar, the dromaeosaur Adasaurus, the bird Brodavis, the ornithomimosaurs Anserimimus and Deinocheirus, and the alvarezsaur Mononykus.
It would have come across Gallimimus, the hadrosaur Saurolophus, the pachycephalosaur Prenocephale, and the tyrannosaur Tarbosaurus in both localities. Crocodylomorphs like Paralligator, fish like Harenaichthys, and turtles could be found in the freshwater lakes.
This art may be used for educational purposes, with credit, but please contact me first for permission before using my art. I would like to know where and how it is being used. If you don’t have something to add that was not already addressed in this caption, please do not repost this art. Thank you!
