Happy #FossilFriday from this cute little tyrannosaur premaxillary tooth! Tyrannosaurs were heterodont (having different forms of teeth) with the premaxillary teeth at the front of the mouth being shorter and more "D-shaped" in cross-section than the rest. Judith River Formation - Montana, USA

Had a crappy day? Well, me too. This is fossilized poo. Coprolites are known from many fossil formations and can be valuable for research. The word "coprolite" is Greek for "dung stone" which is as apt of a name as there is.

I recognize these... At a dinosaur themed Mini Golf business, I saw these two blatant copies of Raul Martin's iconic #PaleoArt. These were far from the only recognizable art lining the walls, but most were of animals from the Jurassic Park franchise. I am curious if anyone else has seen similar

Happy #FossilFriday from the "Icy Crested Lizard" - #Cryolophosaurus! This Antarctica native lived near the beginning of the Jurassic and represents one of the first known theropod dinosaurs to stand taller than your average human. In fact, this photo was my perspective looking up at its toothy grin

An interesting tidbit tucked away in the "Dueling Dinosaurs" paper is that the authors propose the Naturalis Tyrannosaurus "Trix" is roughly the same age (~66.9my old). They base this on microfossils, the specimens occurring at roughly the same stratigraphic height, & being discovered ~8km apart.

He's far from the only one to pose with a firearm. Old-timey paleo + gun = surprisingly common. Another example: O.C. Marsh and his miniature fossil militia circa 1872

The family of armoured dinosaurs, (Thyreophora) was coined by Baron Franz Nopcsa of Austria in 1915. In addition to naming the "shield-bearing" dinos, he is also considered the "father of paleobiology" for his early work in deducing dinosaur behaviour. He's a very interesting figure to research!

Happy #FossilFriday from the enigma that is #Jakapil. It seems to be a ~1 meter long remnant of a very early branch of the armoured dinosaur lineage (containing stegosaurs and ankylosaurs), but many of its features are more similar to other herbivorous dino families. What on Earth was this thing?

Happy #FossilFriday from the South African #Ngwevu! This Early Jurassic Sauropodomorph used to be lumped in with the larger and more common Massospondylus. But, like many other dinosaur species, it was "discovered" by studying already collected fossils assigned to another dino (Chapelle et al, 2019)

New behavioral #paleontology paper out today about tyrannosaur predation! The authors (Wyenberg-Henzler & Scannella) contend that the find is "consistent with a bite inflicted during an attempt to control the struggling Edmontosaurus or deliver a killing blow followed by carcass consumption". Nice!

#Kwanasaurus (Martz & Small, 2019) was native to North America ~210my ago. It belongs to the silesaurids - a clade that is increasingly interpreted as a step in the evolution of the ornithischian dinosaurs. Its leaf-shaped teeth indicate it was already well on its way to herbivory.

Happy #FossilFriday from the West Gold Hill Dinosaur Tracksite in #Colorado! These sauropod footprints are exposed for roughly 100 meters and can be accessed via a hiking trail on public lands! Apart from being a notably long trackway, they are also unique for being at ~2800 meters in elevation

2025 was eventful to say the least... In my world, and why posting Dino Facts has been much less frequent, is my little hatchling arrived! A big shoutout to @adamrl.bsky.social for putting this Rex & chick print for sale so I could hang it in the nursery! Hopefully 2026 is less hectic for us all

The "caudofemoralis longus" is a muscle that leaves obvious evidence of its existence on the bones of dinosaurs. This muscle that retracted the leg during locomotion was anchored to the thigh bone at the 4th trochanter (see pic, labeled "d" where the bone is deformed by musc stresses) & to the tail.

In dinos, you can approximate age based on Lines of Arrested Growth (LAGs) mostly researched in load-bearing bones. They look like tree rings. Notably, when an animal is growing, the rings are wide (showing a period of growth). At adulthood, the rings become small and tightly packed (slowed growth).

The abelisaurid line of carnivorous #dinosaurs likely had a wide range of skin patterns on their head - as noted and mapped by Delcourt (2018). His conclusion: some areas were likely adapted for social behaviours like intraspecies combat. Increasingly armoured heads seem to be a derived trait.

Sorry for the less frequent posting - I have a little human hatchling due soon! On that note: When most people think of dinosaur hatchlings, they think of #Maiasaura from the famous "Egg Mountain" locale in Montana. This was one of the first discoveries exhibiting dinosaur social behavior (1979)

#Weewarrasaurus (illustrated below by PaleoEquii on Wikimedia Commons) was a herbivorous dinosaur from Late Cretaceous #Australia. Interestingly, its only known fossils, consisting of jaw fragments with teeth, were discovered by miners in NSW preserved in opal.

#Aardonyx is a South African sauropodomorph from the Early #Jurassic. Yates et al (2009) describe this dinosaur as being remarkably robust and recover it one of the closest relatives of the true "long-necks" that was capable of walking on just its hind legs. #FossilFriday #paleontology

#Silesaurus and its relatives are looking increasingly like they are either the ancestors of the ornithiscian dinosaurs or are verrrry close relatives. These "dinosauriforms" have been recovered in a lot phylogenies lately as at or near the base of the plant-eating branch of the dinosaurs.

Happy #FossilFriday from a newly named dinosaur! #Istiorachis macarthurae is a iguanodontian with elongate neural spines from the Early Cretaceous on the Isle of Wight! The scientific paper was published yesterday, so I'll need to read this over the weekend. (Lockwood et al, 2025)

Happy #FossilFriday from a hadrosaur foot bone! Presumably Metatarsal IV of a large duck billed dinosaur, this bone was uncovered in Dinosaur Park Fm equivalent rocks in Montana. This is one of many finds coming from a multi-taxic bonebed that used to be a river channel in the Cretaceous. #science

Another fun picture from the field! No fossils here, but a hot lunch is hard to beat some days. Leftovers warmed by the sun will have to do when you're living primitively and digging in remote locations but don't want to eat sandwiches every day. Sandwich fatigue is real. #Paleontology #Fieldwork

A fun anatomical quirk I have noticed is the torso & tail vertebrae of whales have their transverse processes projecting from within the height of the centrum whereas in dinosaurs they project from higher on the neural arch. I do not know if this rule has exceptions or not, but it's neat. #Anatomy

#Sinoceratops is one of the most significant fossil finds very few folks talk about. Known from a partial skull from China, it indicates large ceratopsids were also part of the NA/Asia bio-exchange in the late Cretaceous. How widespread and long-lived were centrosaurines in Asia? (Xing et al, 2010)

Happy #FossilFriday from #Coal! Who needs bones when you can find coal? Often when digging, matted layers of plants and wood are found in the same layers as bone. The insides of logs especially are frequently filled with coal. I've found at least a bucket-full (official measurement) this year...

A fun side-effect of doing field #paleontology in Western North America is the local #wildlife. Often, it's just birds and small mammals. But while hiking to a dig site, you often pass more dangerous friends like this one: If you're lucky, they'll even give you a warning of where they are! How nice

An important part of #paleontology is preparing fossil discoveries for transport. That is where "jacketing" is so important. Creating a protective plaster coating that surrounds the fossil allows for easier/safer transportation to the museums and labs where they can be cleaned and studied.

Happy #FossilFriday from a bit of #Daspletosaurus skull! This is an emerging post-orbital horn - the "brow" bone of the late Cretaceous tyrannosaur. This picture is a few years old, but comes from the Judith River Fm of Montana. Forgive the infrequent posts, summer is digging time!

One of the most obvious ways to differentiate the contemporaneous #Gorgosaurus from #Daspletosaurus is the shape of the orbit. In Daspletos, the eye socket is a vertically-oblong oval. In Gorgos, the orbit is fairly circular. Both lived in western North America ~76mya. #TyrannosaurTuesday