Khaan: Beast of the Week

 This week we will be checking out a dinosaur that gave us insight into its behavior.  Make way for Khaan mckennai!

Khaan was a small birdlike dinosaur that lived in what is now Mongolia during the late Cretaceous period, between 75 and 71 million years ago.  From beak to tail it measured about four feet (1.2 meters) long and its name means "Lord" in Mongolian.  (Doesn't stop dinosaur nerds who are also Star Trek nerds making jokes about it, though.) When alive Khaan was likely an omnivore, eating seeds and plants, but also small animals.  

Watercolor reconstruction of a female and male Khaan mckenai.  There is actual fossil evidence that males of this species may have exhibited courtship dances. (read on)

Khaan was a member of the oviraptorid family, characterized by their overall very birdlike appearance, with long, slender legs and necks, long arms, tipped with hooked claws, and possessing feathers.  They also are known for having unusually blunt skulls with large eye sockets and very short, almost parrot-like beaks.  Many of them also had tall bony crests growing from the front of their faces.  Khaan was a particularly small example of this group, but many, like Citipati were about human-sized, and others, like Gigantoraptor were huge.  

Skull of Khaan on display at the American Museum of Natural History in New York.

Like all oviraptorids, Khaan had a short, tall beak, which many experts think was an adaptation for eating mostly plants when alive.  Others have suggested it was also eating small animals, and even using their seemingly specialized beak for cracking hard-shelled prey like shelled mollusks and crustaceans.  Khaan was actually part of a study that examined the jaws of several kinds of oviraptorids and compared them to those of other kinds of plant-eating theropods, like ornithomimosaurs and therizinosaurs.  This confirmed that for their size, oviraptorids had very powerful bites for their size, and may have been using their jaws for crunching through particularly tough plant material that other, weaker-jawed dinosaurs couldn't access.  

Skeletons of the two Khaan specimens that are thought by experts to represent a male and female.  They may have have even been a pair in life, since they were discovered together. Casts of these skeletons were on display at the American Museum of Natural History in New York for their temporary "Dinosaurs Among Us" exhibit.

Khaan tells us a lot about dinosaur behavior thanks to a few key details about its anatomy.  Two skeletons of Khaan that were adults when they died were discovered right next to each other.  Normally there would be no way to tell if these were the same or different sexes, except for the fact that one of them had slightly longer and differently-shaped tail chevrons (bony extensions on vertebrae) which implies there were more muscles there in life.  This means one of them was using its tail for something the other wasn't.  This had lead to a lot of experts to hypothesize that Khaan may have engaged in courtship dances, like many modern birds do today, like turkeys or grouse, with the males moving their their tails around (probably with feathers on the end) to entice potential partners.  

References

Clark, J. M.; Norell, M. A.; Barsbold, R. (2001). "Two new oviraptorids (Theropoda: Oviraptorosauria), Upper Cretaceous Djadokhta Formation, Ukhaa Tolgod, Mongolia". Journal of Vertebrate Paleontology. 21 (2): 209.

Iv, W. S. P.; Funston, G. F.; Currie, P. J.; Norell, M. A. (2015). "A possible instance of sexual dimorphism in the tails of two oviraptorosaur dinosaurs". Scientific Reports. 5: 9472.

Meade, Luke E.; Ma, Waisum (22 February 2022). "Cranial muscle reconstructions quantify adaptation for high bite forces in Oviraptorosauria". Scientific Reports. 12 (1): 3010.

W. Scott Persons IV; Philip J. Currie; Mark A. Norell (2014). "Oviraptorosaur tail forms and functions". Acta Palaeontologica Polonica. 59 (3).

Glacialisaurus: Beast of the Week

This week we will be looking at a dinosaur that demonstrates how different the world's climate used to be millions of years ago.  Check out Glacialisaurus hammeri!

Glacialisaurus was plant-eating dinosaur that lived in what is now Antarctica during the late Jurassic Period, between 186-182 million years ago.  Although it is only known from a few bones, Glacialisaurus is estimated to have been about 20 feet (6 meters) when from snout to tail.  The genus name translates to "Ice Reptile" in reference to the fact that it was discovered in the now icy Antarctic.  

Watercolor life restoration of Glacialisaurus by Christopher DiPiazza.

Glacialisaurus is considered a basal sauropodomorph, also known as a "prosauropod", which are generally considered the "more primitive" relatives of the long-necked sauropod dinosaurs, like Apatosaurus and Brachiosaurus. Like their more popular relatives, this group of dinosaurs had relatively long necks with small heads.  Unlike them, many of these dinosaurs walked on their hind legs, some being obligate bipeds, and others able to switch between two and four limbs depending on what suited them.  Their robust front limbs ended in five flexible fingers.  The first finger on each hand typically had a particularly long and curved claw, possibly for defense against predators, battling rivals of the same species, grasping branches while feeding, or maybe something completely different nobody's imagined. They had long, somewhat rectangular skulls with slightly downturned jaws, lined with leaf-shaped teeth, ideal for shearing plants.   

All that being said, Glacialisaurus, itself, is only known from a few limb bones, including part of a femur and some of the foot.  Based on these bones, experts can deduct it was a close relative of other basal sauropodomorphs, like Massospondylus.  Its bones were particularly robust compared to many of its relatives, meaning it would have been an overall robust animal for its length.  

Images of Glacialisaurus' foot bones from Smeth Et al. referenced below.

Perhaps the most interesting thing about Glacialisaurus isn't as much about its body but more its habitat, which is now frigid Antarctica.  During the early Jurassic, however, Antarcticta was still attached to South America, Africa, Australia, and India. (India would later separate as an island and eventually crash into southern Asia) It was also closer to the equator at the time, which means it was much warmer than it is today.  This is reflected in the kinds of fossils that have been found, including various plants that are known from warmer climates.  Glacialisaurus also would have coexisted with other animals, including a still unnamed pterosaur related to Dimorphodon, at least one other smaller kind of still unnamed basal sauropodomorph, and the large meat-eating theropod, Cryolophosaurus, which may have hunted it.  

References

Bomfleur, Benjamin; Pott, Christian; Kerp, Hans (2011). "Plant assemblages from the Shafer Peak Formation (Lower Jurassic), north Victoria Land, Transantarctic Mountains". Antarctic Science. 23 (2): 188–208.

Cantrill, David J.; Hunter, Morag A. (2005). "Macrofossil floras of the Latady Basin, Antarctic Peninsula". New Zealand Journal of Geology and Geophysics. 48 (3): 537–553.

Hammer, W. R., & Hickerson, W. J. (1996). Implications of an Early Jurassic vertebrate fauna from Antarctica. The Continental Jurassic, 215–218.

Rauhut, O. W. M.; Holwerda, F. M.; Furrer, H. (2020). "A derived sauropodiform dinosaur and other sauropodomorph material from the Late Triassic of Canton Schaffhausen, Switzerland". Swiss Journal of Geosciences. 113 (1): 8.

Smith, Nathan D.; Pol, Diego (2007). "Anatomy of a basal sauropodomorph dinosaur from the Early Jurassic Hanson Formation of Antarctica". Acta Palaeontologica Polonica. 52 (4): 657–674.

Smith, N.D; Hammer, W.R.; Makovicky, P.J. (2013). "New Dinosaurs from the Early Jurassic Hanson Formation of Antarctica, and Patterns of Diversity and Biogeography in Early Jurassic Sauropodomorphs". Geological Society of America Abstracts with Programs. 45 (7): 405–406.