Peloroplites: Beast of the Week

 This week we will be checking out a large tank dinosaur.  Enter Peloroplites cedrimontanus!

Peloroplites was a plant-eating dinosaur that lived in what is now Utah, USA, during the Cretaceous period, between 98 and 93 million years ago.  From snout to tail it would have measured about 20 feet (6m) long.  It's genus name translates to "Giant Hoplite" in reference to hoplites, the ancient Greek soldiers who famously carried spears and large shields.  The species name translates to "Cedar Mountain" in reference of the geologic location in which its bones were found, the Cedar Mountain Formation.

Peloroplites life reconstruction in watercolor by Christopher DiPiazza.

Peloroplites was a member of the ankylosaur group of dinosaurs, famous for their heavy armored bodies.  More specifically within the ankylosaur group, it was in the nodosaur family, which are known for having spiky armor, especially around their necks.  Unlike more iconic ankylosaurs, nodosaurids lacked bony tail clubs.  Gargoyleosaurus and Priconodon are other examples of nodosaurs.

Peloroplites had a particularly boxy skull, with a snout that slopes down at the front.  The beak was broad and had a little notch in the center of it.  It also possessed blunt horns on its cheek bones in addition to thick bony armor on the top of its head. Only one tooth was found for Peloroplites, and it is typical for nodosaurs, proportionally small and leaf-shaped, for cutting plants.  Because of this dinosaur's noticeably wide face, it may have been a generalist feeder, hoovering up any plant material it could reach. 

Pelororoplites skeletal mount on display at the USU Eastern Prehistoric Museum, in Utah, USA.

A good amount of Peloroplites' skeleton is known, including much of its skull and many limb and other body bones, but sadly very little armor.  Because of this the skeletal ad life reconstructions of this dinosaur have the armor and spikes are based on other nodosaurs which we do have the armor of.  (Special thank you to Dr. Kenneth Carpenter, the paleontologist who originally described Peloroplites, for confirming this for me.)

When alive, Peloroplites' habitat would have been seasonally wet/flooded environment on the western shore of the shallow sea that used to be present down the middle of the United States during the Cretaceous.  It coexisted with many other dinosaurs, including the small tyrannosaur, Moros, and the larger theropod, Siats.  

References

 Carpenter, Kenneth; Bartlett, Jeff; Bird, John; Barrick, Reese (2008). "Ankylosaurs from the Price River Quarries, Cedar Mountain Formation (Lower Cretaceous), east-central Utah". Journal of Vertebrate Paleontology. 28 (4): 1089–1101.

Diamantinasaurus: Beast of the Week

This week we'll be learning about a beast that greatly helps us understand how sauropod dinosaurs ("long-necks") looked and lived.  Check out Diamantinasaurus matildae!

Diamantinasaurus lived in what is now Queensland, Australia during the middle Cretaceous period, between 95 and 92 million years ago.  It's considered medium-sized for a sauropod, and would have measured about 52 feet (16m) long from snout to tail. (Yes. 52 feet is only medium for sauropods!) Like all sauropods it would have eaten plants when alive.  It's genus name is after the Diamantina River, near where its bones were initially discovered.  The species name is after the popular Australian song, "Waltzing Matilda".

Watercolor reconstruction of Diamantinasaurus by Christopher DiPiazza.  Fossil evidence shows this dinosaur wasn't a picky eater, eating a wide variety of plants.

Diamantinasaurus was initially known from limb bones, ribs, and pelvis bones.  It's limbs stand out as being particularly robust, even for a sauropod.  Another interesting feature is the fact that its front limbs possessed short little finger bones and a single large claw on each hand.  These are common traits to most sauropods from earlier times, but were lost in most later sauropods that lived during the Cretaceous period. Diamantinasaurus appears to have retained what is otherwise considered this primitive trait.  

Photograph of the bones in Diamantinasaurus' manus(hand).  Note the prominent claw that grew out of the side of the hand.

Later on after its initial discovery Diamantinasaurus' skull was discovered.  This is exciting since the skulls of sauropods notoriously are hard to find. (they appear to have tended to get separated from the rest of the body and destroyed before fossilization, which makes sense how small they are compared to the bodies) Diamantinasaurus' snout sloped downwards, and actually resembles the skull of Brachiosaurus, even thought it is believed to have been more closely related to fellow Cretaceous sauropods, like Saltasaurus.  A few of Diamantinasaurus' teeth were also found still in the jaw that had not grown in yet, which were narrow and rod-shaped with chisel-like tips.  

Front and side view of the skull of Diamantinasaurus.

More recently in 2025, fossilized gut contents of Diamantinasaurus were discovered.  This is amazing since up until this point, even though everyone assumed sauropods ate plants, actual proof in the form of a fossilized last meal had never been found in one.  As it turns out Diamantinasaurus appears to have been a generalist plant-eater, with remains of all sorts of plants, including ferns, pine trees, and flowering plants found in its stomach.  This means Diamantinasaurus wasn't only feeding at the tops of trees, like sauropods are often depicted doing, but rather was using its long neck to reach all sorts of heights to feed.  Like all sauropods, Diamantinasaurus couldn't chew since its teeth were only at the front of its snout for chomping.  Rather it would have swallowed mouthfuls of plants whole and relied likely on fermentation inside its body to digest the meals.  Some believe that sauropods also could have swallowed stones to help aid in digestion, like some birds and other reptiles are known to do today.

References

Poropat, S.F.; Upchurch, P.; Mannion, P.D.; Hocknull, S.A.; Kear, B.P.; Sloan, T.; Sinapius, G.H.K.; Elliot, D.A. (2014). "Revision of the sauropod dinosaur Diamantinasaurus matildae Hocknull et al. 2009 from the mid-Cretaceous of Australia: Implications for Gondwanan titanosauriform dispersal". Gondwana Research. 27 (3): 995–1033.

Poropat, Stephen F; Kundrát, Martin; Mannion, Philip D; Upchurch, Paul; Tischler, Travis R; Elliott, David A (2021-01-20). "Second specimen of the Late Cretaceous Australian sauropod dinosaur Diamantinasaurus matildae provides new anatomical information on the skull and neck of early titanosaurs". Zoological Journal of the Linnean Society. 192 (2): 610–674.

Poropat, S.F.; Mannion, P.D.; Upchurch, P.; Hocknull, S.A.; Kear, B.P.; Kundrát, M.; Tischler, T.R.; Sloan, T.; Sinapius, G.H.K.; Elliott, J.A.; Elliott, D.A. (2016). "New Australian sauropods shed light on Cretaceous dinosaur palaeobiogeography". Scientific Reports. 6 34467.

Poropat, S. F.; Tosolini, A.-M. P.; Beeston, S. L.; Enchelmaier, M. J.; Pentland, A. H.; Mannion, P. D.; Upchurch, P.; Chin, K.; Korasidis, V. A.; Bell, P. R.; Enriquez, N. J.; Holman, A. I.; Brosnan, L. M.; Elson, A. L.; Tripp, M.; Scarlett, A. G.; Godel, B.; Madden, R. H. C.; Rickard, W. D. A.; Bevitt, J. J.; Tischler, T. R.; Croxford, T. L. M.; Sloan, T.; Elliott, D. A.; Grice, K. (2025). "Fossilized gut contents elucidate the feeding habits of sauropod dinosaurs". Current Biology. 35 (11): 2597–2613.

Daemonosaurus: Beast of the Week

 This week we will be checking out a unique looking early dinosaur with a very cool name.  Meet Daemonosaurus chaoliodus!

Daemonosaurus was a small meat-eating dinosaur that lived in what is now New Mexico, United States, during the late Triassic period, roughly between 205 and 200 million years ago.  From nose to tail it is estimated to have measured roughly 5 to 7 feet (1.5-2.2m).  These are estimates based on the fact that only the skull and neck were found.  The genus name translates to "Demon Reptile" and the species name translates to "Prominent Tooth" in reference to its unusual front teeth.  

Watercolor reconstruction of Daeomonosaurus by Christopher DiPiazza.

The first thing you notice about Daemonosaurus is its unusual face.  It possessed round, short-snouted skull with huge eye sockets, so it probably had sharp vision in life.  It possessed unusually long curved teeth right in the front of its mouth.  In fact, the very frontmost teeth are the longest overall.  The teeth themselves are mostly rounded in cross section with shallow serrations on the anterior sides only.  It is difficult to exactly know what these extreme teeth were adapted for, but it was likely eating some form of meat.  Perhaps it was a fish and other water prey specialist?  Maybe it was snapping up small fast creatures, like insects?  We may never know.

The identity of what kind of dinosaur Daemonosaurus is somewhat mysterious mostly because simply not that many dinosaurs from the Triassic period are known compared to other times.  The Triassic was also a time when dinosaurs were still not clearly diversified into the more distinct forms we recognize from later times.  Initially, when Daemonosaurus was first published on in 2011, it was identified as a theropod dinosaur, closely related to its contemporary, Coelophysis.  This makes sense since they both had sharp curved teeth with serrations, and they even both possess a notch at the front of the upper jaw, which is a common trait among early theropod dinosaurs.  Later on in 2020, however, those same paleontologists who wrote the first paper identifying Daemonosaurus as a theropod revised their stance based on more information, placing it just outside the theropod group as a kind of very early saurischian dinosaur. To review, the saurischian dinosaurs are the broader group that contains both the bipedal theropods and the long-necked sauropods.  This means Daemonosaurus was closer to older dinosaurs, like Herrerasaurus.  Since only Daemonosaurus' skull and neck have been found, we may still learn new things about it and its identity may change yet again in the future! 

Photograph of all the fossil material that is currently known from Daemonosaurus.  Note the long front teeth and huge eye socket. Photo featured in the 2011 paper by Seus et al. referenced below.

When alive Daemonosaurus would have lived in a environment that swung between extreme aridness and heavy rain and flooding during the year.  In fact, the bonebed it was found in is thought to be the result of a flash flood wiping out a bunch of animals.  Daemonosaurus' most common neighbor appears to have been Coelophysis, which it was surrounded by many skeletons of when it was discovered.  It also would have coexisted with the early crocodilian, Hesperosuchus, and the giant predator Postosuchus, to name a few more.

References

Hans-Dieter Sues; Sterling J. Nesbitt; David S. Berman & Amy C. Henrici (2011). "A late-surviving basal theropod dinosaur from the latest Triassic of North America". Proceedings of the Royal Society B. 278 (1723): 3459–3464.

Nesbitt, Sterling J.; Sues, Hans-Dieter (3 August 2020). "The osteology of the early-diverging dinosaur Daemonosaurus chauliodus (Archosauria: Dinosauria) from the Coelophysis Quarry (Triassic: Rhaetian) of New Mexico and its relationships to other early dinosaurs". Zoological Journal of the Linnean Society. 191: 150–179.

Novas, Fernando E.; Agnolin, Federico L.; Ezcurra, Martín D.; Temp Müller, Rodrigo; Martinelli, Agustín G.; Langer, Max C. (2021-10-01). "Review of the fossil record of early dinosaurs from South America, and its phylogenetic implications". Journal of South American Earth Sciences. 110 103341.