Yi: Beast of the Week

 This week we will be checking out a dinosaur that was so unusual, it completely changed what we thought we knew about dinosaur evolution.  Check out Yi qi! (pronounced "EE-chee")

Yi was a small theropod dinosaur that lived in what is now Hebei, in Northeastern China during the late Jurassic period, about 159 million years ago.  From snout to tail it only measured about a foot (30 cm) long and its wingspan was about 2 feet (60cm) wide.  The genus came, "Yi" translates from Mandarin to "wing" and the species name, "qi", means "strange", which is totally appropriate as you are about to find out.  It also fun to note that Yi qi has the shortest full name of any dinosaur.

Watercolor reconstruction of Yi by Christopher DiPiazza.

Yi belonged to the family of theropod dinosaurs, called scansoriopterygidae, which are known for being relatively small, with short snouts and teeth in the front of their jaws that jutted forward, possibly an adaptation for grabbing insects.  They are also known for having feathers and extremely long fingers, often portrayed living in trees.  These traits alone make them stand out among dinosaurs, but what makes Yi even more unusual is the fact that it had a sheet of skin stretching from its fingers and down its arms, which was supported by an extra rodlike bone that grew out of its wrist, forming what can only be described as batlike wings.  Before this we only knew of animals evolving wings three times in vertebrates, bats, pterosaurs, and dinosaurs(feathered wings seen in birds).  Now it turns out that dinosaurs evolved a second completely different version of wings alongside the feathered ones thanks to Yi.  It should also be noted that modern gliding mammals, like flying squirrels possess an elongated piece of cartilage near their wrist, extremely similar to the bone growing out of Yi's.  All of these features suggests Yi was likely at least gliding around when it was alive.  The experts who originally described Yi suggested it may have even been capable of powered flight but more evidence is needed to prove it.  

Diagram showing the homologous parts of the wings of each kind of vertebrate.  Thanks to Yi we know dinosaurs evolved wings at least two separate times.

What makes Yi even more interesting is despite having batlike wings, its body was mostly covered in feathers. The feathers themselves were preserved enough to tell they each comprised of a quill with a little tuft at the top, essentially mini palm tree shaped.  They start almost at the tip of the dinosaur's nose and go down the head and neck, cover the torso extending to the arms, and also on the legs down the shins.  Scientists were also able to find melanosomes (organelles that determine pigment in hair, skin, and feathers) preserved in both the feathers and skin of Yi.  According to the melanosome shapes that preserved, Yi may have had reddish colored feathers on its head, gray or black feathers on its body, and dark gray or black colored skin on its wings. (Keep in mind this is only based on the melanosomes they were able to find.  Sometimes animals have a variety of different melanosomes that when together reflect different colors, some that maybe don't preserve well.)

The unusual appearance of Yi doesn't even there. A close relative of Yi's, called Epidexipteryx, was discovered with four long ribbon-like feathers growing out of its otherwise stumpy tail. Sadly Yi's tail wasn't found, but it is possible it also sported feathers like this.  We can't be sure what they would have been for, likely display of some kind if it was anything like its modern bird relatives. 

Photograph of the found fossils of Yi qi from the paper by Xu et al. referenced below.

All of these unusual traits lead most experts to think Yi was a tree dweller in life.  It could have used its strong arms and long fingers to climb, and probably was able to glide at least short distances between branches.  Its short face and small teeth would have been a good for eating insects, but it may have been omnivorous too, nibbling seeds or other plant matter.  The fossils of many other interesting creatures have been unearthed in the same area as Yi, including fellow dinosaurs, Anchiornis, Eosinopteryx, and Tianyulong, the pterosaur, Darwinopterus, as well as the salamander Chunerpeton, to name a handful. 

References

Dececchi, T. Alexander; Roy, Arindam; Pittman, Michael; Kaye, Thomas G.; Xu, Xing; Habib, Michael B.; Larsson, Hans C. E.; Wang, Xiaoli & Zheng, Xiaoting (2020). "Aerodynamics Show Membrane-Winged Theropods Were a Poor Gliding Dead-end". iScience. 23 (101574) 101574.

Xu, Xing; Zheng, Xiaoting; Sullivan, Corwin; Wang, Xiaoli; Xing, Lida; Wang, Yan; Zhang, Xiaomei; O'Connor, Jingmai K.; Zhang, Fucheng & Pan, Yanhong (7 May 2015). "A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings". Nature. 521 (7550): 70–73.

Sauroposeidon: Beast of the Week

 This week we will be checking out a huge dinosaur with an equally impressive name.  Enter Sauroposeidon proteles!

Sauroposeidon was a sauropod dinosaur (long neck) that lived in what is now Oklahoma, Texas, and Wyoming, USA, during the early Cretaceous period, about 113 million years ago.  Its genus name translates to "Lizard Earthquake God" after the Greek god, Poseidon, who in addition to his more famous association with the ocean, was also the god of earthquakes in Greek mythology. Since not a full skeleton is known, it is difficult to tell exactly how long this dinosaur could get (because necks and tails vary so much in sauropods) but estimates range anywhere between 89 to 112 feet (27-34 m) long, making it one of the largest land animals to ever exist. 

Watercolor of two Sauroposeidon squaring up by Christopher DiPiazza.

Sauroposaidon was originally known from only a few neck vertebra.  That being said these neck vertebra were enormous, the longest of any dinosaur found in fact.  Just one vertebra alone measured 4.6 feet (1.4m)! Later on more bones, including limbs, more vertebra, and even parts of the skull, which were originally referred to as their own genus, Paluxysaurus, were found to actually the same as Sauroposeidon.  Probably the most interesting bit of information regarding this dinosaur's discovery is the fact that some of its limb bones were initially misidentified as fossilized tree trunks!

Photograph of three neck vertebra from Sauroposeidon. (Photo credit: Mathew Wedel)

Sauroposeidon's neck bones were hollow, like those of a bird, and therefore extremely light for their immense size.  This would allow the dinosaur to more easily move its head and neck around without exhausting itself.  This was likely an adaptation for being able to reach leaves at the tops of trees to eat, but also could have been a way for the dinosaur to access a wide range of food without moving its body, thus conserving energy.  Large sauropods, like Sauroposeidon, likely needed to be eating most of the time they were awake in order to fuel their bodies. 

As an adult, Sauroposeidon likely had not predators to worry about.  As a juvenile, however, it may have been preyed on by Acrocanthosaurus, and as babies, it would have needed to watch out for Deinonychus.  It also coexisted with the tiny ceratopsian, Aquilops, and the long-tailed ornithopod, Tenontosaurus.

References

Rose, Peter J. (2007). "A new titanosauriform sauropod (Dinosauria: Saurischia) from the Early Cretaceous of central Texas and its phylogenetic relationships" (web pages). Palaeontologia Electronica. 10 (2). 

Wedel, Mathew J.; Cifelli, R.L.; Sanders, R.K. (March 2000). "Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma" (PDF). Journal of Vertebrate Paleontology. 20 (1): 109–114.

Wedel, Mathew J.; Cifelli, R. L.; Sanders, R.. K. (2000). "Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon" (PDF). Acta Palaeontologica Polonica. 45: 343–388.

Leptoceratops: Beast of the Week

 Today we will be looking at the small ceratopsian dinosaur, Leptoceratops gracilis!

Leptoceratops was a plant-eating ceratopsian dinosaur that lived in what is now Alberta, Canada, during the late Cretaceous period, between 68 and 66 million years ago.  From beak to tail it measured about 6.5 feet (about 2m) and would have been able to walk on four or two limbs when alive. The genus name translates to "small horned face". 

Leptoceratops life reconstruction in watercolors by Christopher DiPiazza.

Leptoceratops was a ceratopsian dinosaur, which means it possessed a strong parrot-like beak and a bony frill on the back of its skull.  Unlike a lot of its larger relatives it didn't have any horns on the nose or over the eyes, but it did have large pointed jugal (cheek) bones which likely supported horns of some kind in life on the tips.  Its lower jaw was extremely deep, implying there were huge muscles there in life, giving it a powerful bite.  In the jaws it sported leaf-shaped teeth which were proportionally the largest of any ceratopsian.  The wear on Leptoceratops' teeth is unique, suggesting its jaws would  have moved back and forth in a circular motion, similar to many herbivorous mammals, but unheard of in any other dinosaur. This unique feeding style, combined with the raw power of its jaws and the sharpness of the beak, may have allowed it exploit a wider range of plant foods since it did not have the height advantage of other larger plant-eaters it coexisted with.  

Diagram of the tooth ware and chewing motion of Leptoceratops from the paper by Varriale et al. referenced below.

Leptoceratops had proportionally shorter but powerful arms, each armed with five strong fingers, the first three of which had claws.  Its hind legs were longer and it was likely capable switching between quadrupedal and bipedal walking and running depending on what suited it.  The vertebra in its tail had long neural arches, forming a tall almost fin-like profile, which may have been an adaptation for display against rivals of the same species or possibly predators, distorting the animal's profile and making it look larger than it really was.  

Two Leptoceratops skeletons on display at the Canadian Museum of Nature

A paper published in 2019 suggests Leptoceratops may have lived underground, thanks to multiple skeletons of different aged individuals found in what appeared to have been a collapsed burrow.  This doesn't seem impossible since Leptoceratop's extremely short frill wouldn't have gotten in the way if it was moving around through tunnels in life.  Sleeping underground is also a great strategy for avoiding predators.  

Despite its size Leptoceratops may have been able to fend off predators by simply being a jerk.  (This is not backed up by any fossil evidence but behavior rarely is.)

When alive Leptoceratops would have shared its habitat with some of the most famous dinosaurs, like Edmontosaurus, Ankylosaurus, Pachycephalosaurus, and Triceratops. It would have needed to watch out for predators like Acheroraptor, Nanotyrannus, and Tyrannosaurus, plus all the crocodilians and large pterosaurs, like Quetzalcoatlus, that were around. (although Quetzalcoatlus may have only been able to prey on babies.)  At first it's easy to imagine little Leptoceratops as nothing more than fodder for these predators since it had no horns or armor, but keep in mind that beak backed up with all that jaw pressure was potentially a devastating weapon.  It's not supported by any true evidence, but I always imagined Leptoceratops as extremely foul tempered and aggressive, even towards animals that dwarfed it, as a defense strategy. Modern Honey Badgers, Wolverines, and even members of the pig family effectively exhibit this strategy today. Even mighty T. rex couldn't have wanted to endure a bite on the toe from a Leptoceratops beak! 

References

Brown, B. (1914). "Leptoceratops, a new genus of Ceratopsia from the Edmonton Cretaceous of Alberta". Bulletin of the American Museum of Natural History. 33 (36): 567–580.

Fowler, D.W.; Wilson, J.P.; Freedman Fowler, E.A.; Horner, J.R. (2019). "The Horned Dinosaur Leptoceratops (Ornithischia: Neoceratopsia) Raised its Young in Communal Nesting Burrows: Evidence from Three New Bonebeds in the Hell Creek Formation (Maastrichtian, Late Cretaceous), Montana" (PDF). Presented Abstracts. Cretaceous and Beyond: Paleontology of the Western Interior. A Symposium Focusing on Cretaceous and Paleogene Vertebrate Paleontology of the Western Interior. 94. North Dakota Geological Survey. Miscellaneous Series: 20.

Maiorino, L.; Farke, A.A.; Kotsakis, T.; Raia, P.; Piras, P. (2018). "Who is the most stressed? Morphological disparity and mechanical behavior of the feeding apparatus of ceratopsian dinosaurs (Ornithischia, Marginocephalia)". Cretaceous Research.

Ryan, M.J.; Currie, P.J. (1998). "First report of protoceratopsians (Neoceratopsia) from the Late Cretaceous Judith River Group, Alberta, Canada". Canadian Journal of Earth Sciences. 35 (7): 820–826.

Varriale, F.J. (2016). "Dental microwear reveals mammal-like chewing in the neoceratopsian dinosaur Leptoceratops gracilis". PeerJ. 4 e2132.