The Mesozoic Mailbag

Edition 1, February 2020

A collection of the latest headlines, species and research in the field of paleontology from January and February of 2020.


It can be difficult to keep track of new discoveries within paleontology! Due to the astonishing rate at which paleontologists work at, new finds can go under the radar at times. Enter my latest idea: The Mesozoic Mailbag! The concept is simple: the mailbag will consist of a collection of the latest headlines, species, specimens or research in the field of paleontology, every second month. Now that this simple introduction is out of the way, let us dive into the Mesozoic Mailbag for January and February of 2020.

The Reaper of Death

Thatatotheristes - Cystoni .jpg
Art Courtesy of Julius Csotonyi

Meet Thanatotheristes Degrootum: the “reaper of death”, and the newest species in the Tyrannosaurid family tree. Unlike other discoveries, the bones of Thanatotheristes weren’t discovered in the field; rather, they were found in a drawer within the Royal Tyrell Museum’s vast fossil collections! Unlike other Tyrannosaurids, this new species has a unique skull that features deep vertical ridges towards the front of its snout. Being a mid-sized Tyrannosaur from the late cretaceous period of Alberta (79.5 million years ago), Thanatotheristes represents a relatively early member of North American Tyrannosaurid lineage. Understanding how this animal came to be the dominant carnivore of its ecosystem may help paleontologists to understand how later Tyrannosaurids were able to thrive as well.

 Dinosaurs with tumours

Did Dinosaurs have similar diseases to that of humans? According to the fossils of a new Hadrosaur specimen, it would seem that they did. The tail of this duck-billed dinosaur possessed a series of unusual holes towards the center of the bone. The abnormal nature of these holes led paleontologists to question as to whether or not they were caused by a disease that affected the living animal. Upon closer investigation, paleontologists were able to compare this dinosaur’s affliction as Langerhans cell histiocytosis (LCH), a rare disease that can lead to benign (largely non-fatal) tumours developing in the body. This disease typically affects human children, and as such it is quite interesting to see such a disease present on a 75 million-year-old dinosaur. This find shows that dinosaurs weren’t the impervious monsters that we often picture them as, and some of them even shared some rare diseases that afflict Humans in the present.

The New Allosaurus on the Block

For almost 150 years it was believed that only one species of Allosaurus Allosaurus Fragillis – called the Morrison formation of the American Midwest home during the late Jurassic period. Now after careful examination of the skeletal features of multiple individuals, a new species of Allosaurus has been unveiled. Named Allosaurus Jimmadseni after Utah State paleontologist James Madsen Jr., this new species represents a much older dinosaur than the other species of Allosaurus, living approximately 5 million years before Allosaurus Fragillis. Aside from the age of the new species, the features of the skull are slimmer and possess a distinct crest when compared to other members of the genus Allosaurus. In its life, Allosaurus Jimmadseni would have been the top predator of its era, as numerous specimens have been discovered. This revelation has increased the diversity of late Jurassic theropods, adding to our understanding of the diverse ecosystem within the Morrison formation.

Big Al 1.jpg
The Infamous “Big Al” Allosaur, now identified as Allosaurus Jimmadneni

And so that concludes the first edition of The Mesozoic Mailbag! While in this post I talked about a few of the most interesting finds to have been announced in January and February of 2020, there are always other interesting finds that may be reserved for future articles (hint hint). With that, I sign off from The Mesozoic Mailbag. 


Voris, Jared. “’Reaper of Death’ Tyrannosaur Discovered in Canada.” National Geographic, 10 Feb. 2020,

University of Utah. “New Species of Allosaurus Discovered in Utah.” EurekAlert!, 24 Jan. 2020,

Rothschild, B.M., Tanke, D., Rühli, F. et al. “Suggested Case of Langerhans Cell Histiocytosis in a Cretaceous dinosaur”. Sci Rep 10, 2203 (2020).

Chung, Emily. “This Weird Disease in Humans Has Existed since the Age of Dinosaurs | CBC News.” CBCnews, CBC/Radio Canada, 18 Feb. 2020,

Thanatotheristes Artwork Courtesy of Julius Csotonyi:

Black, Riley. “Newly Discovered Tyrannosaur Was Key to the Rise of Giant Meat-Eaters.”, Smithsonian Institution, 10 Feb. 2020,

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