#thescelosaurid

[dinosaurs-dinosaurs-dinosaurs]

Thescelosaurus appreciation post. All images from wikipedia. 

[a-dinosaur-a-day]

Talenkauen santacrucensis

By Jack Wood on @thewoodparable

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Name: Talenkauen santacrucensis

Name Meaning: Small Skull

First Described: 2004

Described By: Novas et al. 

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Thescelosauridae, Thescelosaurinae, Elasmaria

Continuing on our theme of “man, the Boyd analysis lead to some weird realities,” here is our third Iguanodont-turned-Thescelosaurine, Talenkauen. It is known from a fragmentary skull and partial skeleton, from the Pari Aike Formation in Santa Cruz, Argentina. It dates back to the Cenomanian age of the Late Cretaceous, approximately 96.2 million years ago. It had thin plates along the sides of its ribs like some other Thescelosaurines, and it had a fairly long neck and still had teeth at the tip of its beak. It lived alongside dinosaurs such as Puertasaurus and Orkoraptor, and was approximately 4 meters long. 

Sources:

Boyd, C. A. 2015. The systematic relationships and biogeographic history of ornithischian dinosaurs. PeerJ 3:e1523 https://doi.org/10.7717/peerj.1523.

https://en.wikipedia.org/wiki/Talenkauen

Shout out goes to @katzalex2!

[a-dinosaur-a-day]

Macrogryphosaurus gondwanicus

By José Carlos Cortés on @ryuukibart​

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Name: Macrogryphosaurus gondwanicus

Name Meaning: Big Enigmatic Reptile

First Described: 2007

Described By: Calvo et. al. 

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Thescelosauridae, Thescelosaurinae, Elasmaria

So by far the weirdest consequence of the recent Boyd study is that the Elasmarians - previously regarded as a group of Iguanodonts, or the more derived members of Ornithopoda - have since been placed completely outside of Ornithopoda, not only in Neornithischia, but as Thescelosaurines. It gets weirder here with Macrogryphosaurus, which is such a large and Iguanodontian-like animal that one would never guess that it might be a Thescelosaurine (of course, the Boyd study does need to be repeated, however, so many Ornithopod and Iguanodontian categories ended up being somewhat wastebasket like, that I will go with this study until further notice). In fact, it with other southern-hemisphere Thescelosaurines forms a strange group known as Elasmaria. Macrogryphosaurus was found in the Portezuelo Formation in Patagonia, Argentina, dating back to the Turonian age of the Early Cretaceous, around 93 to 89 million years ago. It was around 6 meters long, and was the largest Thescelosaurid known. It was probably mainly bipedal, however, it probably was able to move on all fours when necessary. 

Sources:

https://en.wikipedia.org/wiki/Macrogryphosaurus

Boyd, C. A. 2015. The systematic relationships and biogeographic history of ornithischian dinosaurs. PeerJ 3:e1523 https://doi.org/10.7717/peerj.1523.

Shout out goes to @heystooopid!

[a-dinosaur-a-day]

Thescelosaurus neglectus, T. garbanii, T. assiniboiensis

By Jack Wood on @thewoodparable

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Name: Thescelosaurus neglectus, T. garbanii, T. assiniboiensis

Name Meaning: Godlike Reptile

First Described: 1913

Described By: Gilmore

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Thescelosauridae, Thescelosaurinae

Thescelosaurus was a small Neornithischian that is relatively famous, given it’s presence in Hell Creek alongside such famous dinosaurs a Tyrannosaurus rex. It is also known from amazingly well preserved remains, including Willo, a Thescelosaurus preserved with what was thought to be a heart. CT imagery was used to examine the heart multiple times, and histology, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy was used; however, the findings revealed that it probably wasn’t a heart at all, but a concretion of sand during burial - this matters very little, since modern dinosaurs (birds) and the closest relatives to modern dinosaurs (crocodilians) both have four chambered hearts, though they’re modified in crocodilians. Furthermore, most recent studies find that dinosaurs were at least mesothermic, and those that find them to be mesothermic usually underestimate growth rate, indicating that dinosaurs were, only the whole, endothermic (warm-blooded). 

Sorry Willow. Photo by Ryan Somma

Anyway, back to business. Thescelosaurus was a robust, bipedal Ornithischian, growing to anywhere between 2.5 and 4.0 meters in length. It had short, broad hands with five fingers, and it had large thin plates found next to the ribs that probably did not not play a role in respiration, though their role is not clear. Though scutes were once thought to belong to the genus, they have not been found with any other specimen of Thescelosaurus, and were probably crocodilian in origin; given its phylogenetic position, it is more likely that it resembled Kulindadromeus, with a mixture of feathers and scales. It had a long, narrow beak, and it may have had muscular cheeks. It even had two types of teeth: small pointed teeth in the upper jaw and leaf shaped teeth in the cheeks. 

By Leandra Walters, Phil Senter, and James H. Robins

As for the differences between the three species, Thescelosaurus is decidedly the best known among them. Thescelosaurus assiniboiensis is only known from a single specimen, originating in the Frenchman Formation in Saskatchewan, Canada, dating to the late Maastrichtian age of the Late Cretaceous, approximately 66 million years ago. Thescelosaurus garbanii is known from fragmentary remains, however, it would have been the largest of the three, reaching lengths of about 4.5 meters. T. garbanii was found in the Hell Creek formation, in South Dakota, around 66 million years ago. T. neglectus, the type species, is the best known of the three. Found in the Lance Formation in Wyoming, it also dates to the end of the Maastrichtian age, around 66 million years ago. All three have been found to clade together, making this a monophyletic genus; furthermore, all three have been found to be distinct from one another in a phylogenetic analysis by Boyd this past year. 

(From Boyd’s Analysis) 

As such, this genus is only known from Maastrichtian age rock; in addition to the Lance Formation, T. neglectus is also known from the Laramie Formation of the same time period in Colorado, as well as the Scollard Formation of that time in Alberta. This was, as such, a widespread bipedal animal, filling similar niches in similar ecosystems as the Mesozoic era drew to a close. It was one of the last genera of non-Neornithean dinosaurs, and though teeth similar to the teeth of Thescelosaurus have been found in older rocks, they were more likely from its cousin, orodromeus, than they were from Thescelosaurus. However, it was a very common animal, with more skeletons known than have been officially described. 

By me! I went to Burpee and got this photo during PaleoFest, which was a real blast.

Thescelosaurus and its relatives in general have been up to quite a bit of taxonomic scrutiny, with the most recent robust analysis placing them outside of the the Ornithopoda. Given that small, bipedal Ornithischians have often been lumped into Ornithopoda without a second though; with many of them -including Thescelosaurus - being stashed away in the so-called Hypsilophodontid clade, this is hardly surprising. However, this group has increasingly been found to not be a natural one; with many members (the Thescelosaurids in particular) found to be Neornithischians - more closely related to Marginocephalians and Ornithopods than to Thyreophorans like Stegosaurus, however, not true Ornithopods. Many former Hypsilophodonts have been found, in that vein, to be Thescelosaurids, featuring many seemingly basal traits to Ornithischians, as well as derived traits. 

By José Carlos Cortés on @ryuukibart​

Thescelosaurus was, as stated, a very common small herbivore, and probably lived in a flat floodplain, in a dry subtropical climate with a wide variety of plant material to consume. It is also possible that it preferred channels, however, more evidence seems to point in the direction of floodplain habitats for Thescelosaurus. There have not been any bonebeds or accumulations of multiple individuals found, indicating that it may not have been a social genus; though that cannot be entirely ruled out. It lived alongside many other types of dinosaurs including some of the most famous. In the Scollard Formation, T. neglectus was found alongside Troodontids, Dromaeosaurids, Tyrannosaurus, Ankylosaurus, Edmontosaurus, Leptoceratops, Pachycephalosaurus, and Triceratops. In the Lance, T negelctus lived alongside many dinosaurs such as Ceramornis, Cimolopteryx, Graculavus, Lonchodytes, Palintropus, Ptoamornis, Torotix, Troodontids, Ornithomimids, Tyrannosaurus, other indeterminant Avialans, Ankylosaurus, Denversaurus, Leptoceratops, Nedoceratops, Pachycephalosaurus, Torosaurus, Triceratops, and Edmontosaurus. In the Laramie Formation, T. neglectus lived alongside Dromaeosaurus, a Nodosaurid, Edmontosaurus, Ornithomimus, Paronychodon, Torosaurus, Triceratops, and Tyrannosaurus. T. garbanii and T. negelctus in Hell Creek lived alongside many dinosaurs, but similar to the others: Ankylosaurus, Denversaurus, Pachycephalosaurus, Sphaerotholus, Leptoceratops, Tatankaceratops, Torosaurus, Triceratops, Edmontosaurus, Tyrannosaurus, Struthiomimus, Ornithomimus, Anzu, Leptorhynchos, Acheroraptor, Avisaurus, Cimolopteryx, Dakotaraptor, Brodavis, Potamornis, and other indeterminant Avialans. Finally, T. assiniboiensis lived alongside Edmontosaurus, Torosaurus, Triceratops, and Tyrannosaurus. This indicates Thescelosaurus’ important, fundamental role in the typical end-Mesozoic ecosystems of North America. 

You’ll probably even see it with these nerds. From @saurian-game

Sources:

https://en.wikipedia.org/wiki/Thescelosaurus

Boyd, C. A. 2015. The systematic relationships and biogeographic history of ornithischian dinosaurs. PeerJ 3:e1523 https://doi.org/10.7717/peerj.1523.

Shout out goes to @dredelagnesallthetime!

[a-dinosaur-a-day]

Parksosaurus warreni

By José Carlos Cortés on @ryuukibart​

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Name: Parksosaurus warreni

Name Meaning: William Parks’ Reptile

First Described: 1937

Described By: C. M. Sternberg

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Thescelosauridae, Thescelosaurinae

Parksosaurus was a Thescelosaurid known from the Horseshoe Canyon Formation in Alberta, Canada. It lived about 70 million years ago, in the Campanian age of the Late Cretaceous, and it would have been approximately 2.5 meters long and less than one meter tall. It was probably a lighter animal than Thescelosaurus, it’s close relative, given its different body proportions. It had robust hindlimbs and an elongate skull, allowing for it to be a fast runner and low browser like other members of its family. It would have lived alongside many other dinosaurs, such as Albertosaurus, Saurolophus, Hypacrosaurus, Anodontosaurus, ceratopsians, and troodontids. It would have lived along the Western Interior Seaway and would have been affected by this marine ecosystem in its habitat. It may have used its long toes to walk over mud and clay near the seaway and rivers, and used its arms for burrowing. 

Sources:

https://en.wikipedia.org/wiki/Parksosaurus

Boyd, C. A. 2015. The systematic relationships and biogeographic history of ornithischian dinosaurs. PeerJ 3:e1523 https://doi.org/10.7717/peerj.1523.

Shout out goes to @plasticfangs!

[a-dinosaur-a-day]

Zephyrosaurus schaffi

By Jack Wood on @thewoodparable

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Name: Zephyrosaurus schaffi

Name Meaning: Westward Wind Reptile

First Described: 1980

Described By: Sues

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Thescelosauridae, Orodrominae

Zephyrosaurus is a very fragmentary Orodromine known from the Clovery Formation of Carbon County, Montana. It lived in the Aptian age of the Early Cretaceous, about 120 million years ago. It is known from poor, fragmentary remains that have not been extensively studied, though it has been been found to be closely related to Orodromeus. It may have possessed similar burrowing characteristics as Oryctodromeus, and it probably would have been a small, swift, bipedal herbivore like other members of this group. 

Sources: 

Boyd, C. A. 2015. The systematic relationships and biogeographic history of ornithischian dinosaurs.https://peerj.com/articles/1523/

https://en.wikipedia.org/wiki/Zephyrosaurus

Shout out goes to @permanentlycanned!

[a-dinosaur-a-day]

Orodromeus makelai

By Jack Wood on @thewoodparable

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Name: Orodromeus makelai

Name Meaning: Mountain Runner

First Described: 1988

Described By: Horner & Weishamepl

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Thescelosauridae, Orodrominae

Orodromeus is a Thescelosaurid known from the Two Medicine Formation in Montana, dating back to the Campanian age of the Late Cretaceous, around 75 million years ago. It was found alongside Maiasaura specimens and is known from many skeletons as well as eggs, including one with an embryo inside. It was a fast, small herbivore, around 2.5 meters long. It may or may not have been a burrower. Sadly, most of the information known about this genus stems from an unpublished thesis. 

Source:

Boyd, C. A. 2015. The systematic relationships and biogeographic history of ornithischian dinosaurs. https://peerj.com/articles/1523/

https://en.wikipedia.org/wiki/Orodromeus

Shout out goes to @reallyglitteringstardust!

[a-dinosaur-a-day]

Albertadromeus syntarsus

By José Carlos Cortés on @ryuukibart​

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Name: Albertadromeus syntarsus

Name Meaning: Alberta Runner

First Described: 2013

Described By: Brown et al. 

Classification: Dinosauria, Ornithischia, Genasauria, Neornithischia, Thescelosauridae, Orodrominae

Albertadromeus is a Thescelosaurid known from the Oldman Formation of Alberta, Canada, dating back to the Campanian age of the Late Cretaceous, approximately 77 million years ago. It is known from limited remains that do not include the skull, but was found to be more closely related to Orodromeus than to Thescelosaurus, playing it in the Orodrominae. It lived in a coastal plain, near many other dinosaurs such as Saurornitholestes, Daspletosaurus, Troodon, Dromaeosaurus, Albertaceratops, Chasmosaurus, Anchiceratops, Coronosaurus, Brachylophosaurus, Gryposaurus, Parasaurolophus, and Corythosaurus. It would have had the niche of a fast, small, low browser. 

Source:

https://en.wikipedia.org/wiki/Albertadromeus

Shout out goes to @notsomajestic!