An ongoing dinosaur encyclopedia. I also run A Pterosaur A Day.

A Dinosaur A Day

A Field Guide To Dinosaurs



@calytrixas replied to your post: I’ll be back soon! i’m just adjusting …

Tell us if you get a burst of followers during your inactivity. I want to confirm a suspicion. :)





Haha cool. I think when you’re inactive for a while you get put up as a recommended blog much more, perhaps to lure you back into Tumblr.

Weeeeeeird I mean I’m always going to come back I’m just a student so I get busy sometimes

@calytrixas replied to your post: I’ll be back soon! i’m just adjusting …

Tell us if you get a burst of followers during your inactivity. I want to confirm a suspicion. :)





I’ll be back soon! i’m just adjusting to school!




Coming soon:, launched by entrop-e, shychemist, and geogallery, is Tumblr’s project for promoting science education around the world.

At SciNote, we believe that science shouldn’t just be reading about the ideas of people with PhDs and Nobel Prizes. We believe that science is an active process of asking questions and finding answers.

That’s why we, at SciNote, want to hear from you. We want to ponder the interesting questions you pose and get excited with you over the cool science you see in your world.

SciNote will feature the best of the Tumblr science community, and we will compile and publish the top posts from every year in the form of a magazine available both digitally and in print. Think of SciNote magazine as the Tumblr science magazine.

We hope to celebrate our launch by featuring some of the coolest science from around Tumblr. So before we launch SciNote, we would like to collect 25 science posts and/or questions from you, including:

  • the most interesting science news you have come across
  • questions you’ve always wanted to ask
  • fascinating facts that you’ve learned
  • pictures of nature and/or science that you’ve taken
  • cool research that you’ve participated in
  • any other science-related thing you’d like to tell us!

So please:

  1. Submit posts or ask questions to be featured on our blog and for an opportunity to be published in SciNote magazine.
  2. Follow our blog at
  3. Read more about our project here.
  4. If you’re interested, apply to join our staff here.
  5. Reblog this post so that we can collect 25 posts and launch our project as soon as possible!

Thank you all and happy science!


Thank you all so much for your support of SciNote’s mission to promote science education!

In less than 2 days, we have received over 20 applications to join our staff, 14 submitted posts and questions, and immeasurable amounts of support and encouragement. We are incredibly impressed with your passion for science; we are even more confident that, together, we can connect the world though science.

We have very important news for you: SciNote has confirmed its first partner school, Our Lady of the Angels in Kigali, Rwanda! We are thrilled to announce that, throughout the school year, we will be featuring posts from students at OLA on and in SciNote magazine as part of the international science network we hope to build. We hope you are as excited as we are! In the meantime, to read more about Our Lady of the Angels, please click here.

Thank you all again and please continue reblogging and submitting posts— we love hearing from you!

Exciting news everyone! :D Read the update above.

(via thisisdinostuck)

Moving is a bitch

It’s especially hard when you do it four times in one year

Pisanosaurus mertii



NamePisanosaurus mertii 

Name Meaning: Merti & Mr. Pisano’s lizard

First Described: 1967

Described By: Casamiquela

ClassificationDinosauria, Ornithischia, Pisanosauridae 

My Twelfth Favorite Dinosaur! 

Oh look another basal dinosaur what a surprise. Pisanosaurus is considered to be the basalmost ornithischian, or at least the basalmost one known to date. It lived between 228 and 216.5 million years ago in the Norian age of the Late Triassic period. It was found in the Ischigualasto Formation in Argentina and it was a small, lightweight, bipedal herbivore about 1 meter long. Its classification has been under a lot of debate but the current consensus is that it is the oldest known ornithischian. It is only known from a single skeleton that is known from a partial skull and some teeth, some vertebrae, and other bones including part of the pubis, allowing for its classification. Given the synapomorphic character of protofeather/feather like integuments it probably was covered with them in at least some parts of its body. It lived in a volcanically active floodplain that was covered with forests and was warm and humid, but subject to seasonal rainfalls. It probably ate the vegetation of the area which consisted of ferns, horsetails, and conifers. Its major predator was probably Herrerasaurus, which was the most common predator in the area. Pisanosaurus lived right alongside therapsids, rhynchosaurus, dicynodonts, traversodontids, rauisuchians, archosaurus, Saurosuchus, and Eoraptor as well as Herrerasaurus. Herbivorous dinosaurs such as Pisanosaurus were definitely in the minority. 




Shout out goes to anonbinarywolf!

I have a Confession to Make

My tenth favorite dinosaur is Allosaurus 

which I have already done 

And my eleventh favorite dinosaur is Megapnosaurus 

which I have already done 

I’ve been sitting here at my desk debating and mulling and wondering what to do

What I will do 

Is my 12th favorite dinosaur 


Leptoceratops gracilis


NameLeptoceratops gracilis 

Name Meaning: Slender Little Horned Face

First Described: 1914

Described By: Brown

ClassificationDinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Marginocephalia, Ceratopsia, Neoceratopsia, Leptoceratopsidae

My Ninth Favorite Dinosaur!

Leptoceratops was a tiny little dinosaur, about 2 meters long, and it came from Red Deer Valley in Alberta, Canada, as well as locations in Wyoming, USA. It lived in the Maastrichtian age of the Late Cretaceous, about 66.8 to 66 million years ago, showing how even though it appears to be a more basal ceratopsian, it really was not. It probably ran and stood on its hind legs, and even though they couldn’t pronate their forelimbs, they could walk on four legs as well. It is known from several specimens, some of them complete. It was probably a herbivore, given the wear of its teeth and the depth and shortness of its jaw, which would have allowed it to have a powerful bite and chew very powerfully on tough plant matter. Since it was so short, it would have been a low feeder, eating flowering plants as well as ferns and confers. Its classification is pretty uncertain given both its shape and its late position in the time scale. 



Shout out goes to devinhoo!

While refusing to talk about Russel's dinosauroid is perfectly understandable, did you ever see Nemo Ramjet's dinosauroid? Not only it seems more plausible, it's also far more pleasant to look at. Sincerely, Anonymous

I hadn’t seen it, but now I have! It looks awesome!


Troodon formosus, T. inequalis, T. asiamericanus



NameTroodon formosus, T. inequalis, T. asiamericanus 

Name Meaning: Wounding tooth

First Described: 1856

Described By: Leidy

ClassificationDinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Troodontidae

My Eight Favorite Dinosaur 

Troodon is famous for being one of the smartest dinosaurs based on their cerebrum to brain volume ratio, and as such its brain was comparable in part to that of modern birds. It had bony tympanic membranes in its inner ear. It also lived pretty late in the Mesozoic, from 77.5 to 69 million years ago in the Campanian to the Maastrichtian age of the Late Cretaceous. It also possibly lived later, as shown in the documentary Dinosaur Revolution. I’m not crying over the poor Troodon in that documentary. I just have a twig in my eye, or a log. It had teeth with prominent, wounding serrations, which was unique at the time of its discovery and very similar to those of herbivores, suggesting that Troodon was at least partially omnivorous. It was fairly small, only 2.4 meters long, and about 2/3 the height of an average man. It had very thin legs, implying that it could run fairly fast, raising its retractable claws up off the ground when doing so. 



The animaly Stenonychosaurus is actually another species of Troodon, and trust me, if Troodon had been able to continue to evolve and evolved sentience, it would not have evolved to look anthropormophic (like a human) as Dale Russell said.I mean seriously can you imagine a more egotistical thing to think? That the way we look is obviously the only way a sentient being can look? Jesus Mary Joseph and all the freaking saints. Yes, I grew up Catholic. Yes, I still sometimes swear like a Catholic. Please move on. Troodon is one of the most derived members of its family and pretty much with 100% certainty had feathers, given its close relationship to birds and the general feathered state of clades much more basal than Troodontidae. It was found in many different places such as the Two Medicine Formation of Montana, the Dinosaur Park Formation and Horseshoe Canyon Formation of Alberta, the Prince Creek Formation of Alaska, the Hell Creek Formation, Lance Formation, and Scollard Formation. It probably favored cooler climates given its distribution and abundance in the north and even Arctic areas. It also has possibly found more further south in the Javelina Formation in Texas and the Kirtland Formation in New Mexico. 



It probably was a predator in some form given that it had a sickle claw on its foot and good binocular vision, however it was also probably an omnivore given its teeth and the shape of its jaw, which was similar to that of an iguana (and iguanas are herbivores.) The large serrations that indicated it could eat plants are called denticles, and its grasping hands and large brain are actually characteristics shared with herbivorous omnivorous mammals like primates and the raccoon. In northern sites Troodon actually has much larger teeth than ones in southern sites, indicating that it was larger in the north and able to hunt larger animals for prey given that there were fewer tyrannosaurids up there. Furthermore, the lack of wear in the north indicates mainly soft food - so it probably just ate meat in these climates and not tough plant matter. It reached adult size in 3-5 years. 



Troodon nests and eggs have been discovered. The nests were built from sediments and were disc shapes, and had between 16 and 24 eggs. The eggs were shaped like elongated teardrops, with the tapered ends pointed downward and imbedded in the sediment. The reproductive biology of Troodon is somewhere intermediate between crocodiles and birds- the eggs were grouped in pairs which would suggest that it had two oviducts like crocodiles, unlike birds which have one; Troodon also laid eggs of medium size and medium number, unlike crocodiles who lay many small eggs, and birds who lay few large eggs. It also potentially laid eggs iteratively, laying a pair of eggs every one or two days, and delaying brooding until all eggs were laid to ensure that all of them hatched at once. The embryos had advanced skeletal development, implying that they were precocial (or, relatively mature and mobile young), and probably didn’t remain in the nest after hatching. Given the body ratio to egg volume, it actually was very likely that the males in a pair brood the eggs and the females did not, a characteristic that maniraptoran dinosaurs and basal birds probably shared. 



Again, I refuse to talk about “the dinosauroid” more than it’s a dumb, dumb concept. 


Shout out goes to free-my-wonderland!

Scutellosaurus lawleri


NameScutellosaurus lawleri 

Name Meaning: Lawler’s Little-shielded lizard 

First Described: 1981

Described By: Colbert 

Classification: Dinosauria, Ornithischia, Genasauria, Thyreophora

My Seventh Favorite Dinosaur!

I love me some more basal dinosaurs! Scutellosaurus is an early threophoran (the group that includes ankylosaurs and stegosaurs) that lived in the Sinemurian to Pliensbachian ages of the Early Jurassic, about 196 million years ago. It was bipedal, a rare trait for thyreophorans; it was closely related to Scelidosaurus, which was quadrupedal. It is in fact the basalmost thyreophoran. It was about 1.175 meters long. It was lightly built, with a very long tail that would allow counterbalance against the weight of its armored body, and it had long arms that would have allowed it to walk on all fours. Its scutes running down its body formed parallel rows. It was found in the Kayenta Formation in Arizona, USA, and is known from two individuals. It lived alongside Megapnosaurus and Dilophosaurus, which probably preyed on this little guy. 



Shout out goes to margotetsonchatphilippot!

Parasaurolophus walkeri, P. tubicen, P. cyrtocristatus


NameParasaurolophus walkeri, P. tubicen, P. cyrtocristatus

Name Meaning: Near Crested Lizard 

First Described: 1922 

Described By: Parks 

ClassificationDinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Ornithopoda, Iguanodontia, Dryomorpha, Ankylopollexia, Styracosterna, Hadrosauriformes, Hadrosauroidea, Hadrosauridae, Euhadrosauria, Lambeosaurinae, Parasaurolophini 

My Sixth Favorite Dinosaur 

There is no real need to explain why Parasaurolophus is cool. It’s one of those dinosaurs that we actually know how it sounded. It had a badass crest and complex social groups. Holy crap. It lived about 76.5 to 73 million years ago, in the Campanian stage of the Late Cretaceous. It lived in many different places - Dinosaur Park Formation in Alberta, Canada; the Kirtland Formation in New Mexico, USA, and the Fruitland Formation in Utah, USA. This is a completely iconic hadrosaur species and it was about 9.5 meters long in the largest individuals. The crest was probably used to distinguish between members of different species and of different sexes, for audible communication, and even thermoregulation. Despite its fame, it’s actually a relatively rare hadrosaur, known from a few specimens. It was a facultative quadruped, and it had high neural spines that increased the height of its back. Skin impressions are known for P. walkeri, showing uniform scales but no other structures. Its crest is connected to its nose, and may or may not have had a skin flap connecting it to the neck, though this is not confirmed. The hollowness of the crest is notable in that it would have permitted sound to pass through it.  


The type species is known from only one fossil, but the other two species have at least three specimens to their names, with P. tubicen being the largest, and having the most complex air passages in its crest. P. cyrtocristatus was the smallest, with a short rounded crest. P. walkeri had the characteristic long, unrounded crest, and longer upper arms. Charonosaurus has begun to be considered instead of a very closely related genus, another species of ParasaurolophusP. jiayensis, which would make it the first non-North American species. Parasaurolophus was present in many different habitats. In Alberta, it lived along side Centrosaurus, Chasmosaurus, Gryposaurus, Corythosaurus, Gorgosaurus, Edmontonia, Euoplocephalus, and Dyoplosaurus, and was a rare part of the fauna. 


In New Mexico, P. crytocristatus lived with Utahceratops, Kosmoceratops, Pentaceratops, Ornithomimus, and teratophoneus. The larger species P. tubicen lived with Alamosaurus, Krotsaurus, Pentaceratops, Nodocephalosaurus, Sauronitholestes, and Bistahieversor. The Kirtland Formation in particular would have been a large floodplain with many conifers. In Utah, it lived in a plateau area near the Western Interior Seaway, a large floodplain with channels and peat swamps, ponds, lakes, and highlands. it was a wet and humid climate and a very diverse environment. Parasaurolophus lived alongside dromaeosaurids, talos, Ornithomimus, Albertosaurus, Teratophoneus, ankylosaurids, Gryposaurus, Utahceratops, Nasutoceratops, Kosmoceratops, and Hagryphus.

Source: Me. This is Max (my boyfriend) playing with the Parasaurolophus model in the Field Museum. One of my favorite photos. 

Parasaurolophus would have eaten plants while chewing, with constantly replaced teeth that were packed together into batteries with hundreds of teeth. It could crop plant life with its beak, and had a narrow beak for selective feeding. It crest was definitely for multiple purposes, and it’s not sure which purpose was the most important in its evolution. Its crest changed with age and was sexually dimorphic, however the major divergences in crest shape and length have been determined as differences in species. A small tubular crest was present in juveniles, with most of the supporting bones also smaller indicating that it had not yet reached maturity. However, Parasaurolophus crests started developing at a younger crest than its relatives such as Corythosaurus, showing how its crest could get so big in its lifespan. 

Source: Me again; Field Museum fossil of P. crytocristatus 

The crest was definitively not used for an aquatic lifestyle or any sort of amphibious lifestyle, and it was not used for moving or supporting the head. It also wasn’t a foliage deflector, a weapon, for housing specialized organs or salt glands, or expanded areas of olfactory tissue, or throwing jets of chemical fire at enemies. Yes. These were all hypotheses proposed over trumpet. I’m as baffled as you are. It was for auditory and visual communication and, given its size, gave a clear visual signal. Given that the animal had large eye sockets and sclerotic rings that means it would have had acute vision and diurnal habits, sight was very important for Parasaurolophus. Based on scans of their inner ears, it was found that they had a very well developed inner ear, and could hear high frequencies, allowing them to hear the chirps of their young as well as the calls made by other members of the species with their crests. Finally, the intense vascularization of the crest would have allowed the brain to be kept cool. 


I had to. 


Shout out goes to riddikulus-darren!

<A Dinosaur A Day 


A Pterosaur A Day

will officially return

TOMORROW, August 18th>


Sue’s discovery day was yesterday… here is me and Max from a little over a year ago with her 

My favorite T. rex specimen and my favorite person 

What more could you want :)