#dinosauriform

Something quick and ridiculous I did for @a-dinosaur-a-day‘s Kulinday event. 

The sign reads: “A Spoiled Rotten Kulindadromeus lives here.” Little do they know there are two more hiding in a trenchcoat. The handwriting at the bottom reads: DINOSAURS ARE FEATHERED. DEAL WITH IT.  Hey, if all my relatives and I were misrepresented constantly, I’d be grumpy too.

By José Carlos Cortés on @quetzalcuetzpalin-art​

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Name: Nyasasaurus parringtoni

Name Meaning: Lake Nyasa Reptile

First Described: 2013

Described By: Nesbitt et al. 

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Dinosauria?

Nyasasaurus is one of the more fascinating fragmentary animals simply because of its fragmentary nature - and its age. Nyasasaurus is from the Manda Formation of Tanzania, living about 243 million years ago, in the Anisian age of the Middle Triassic. Now, this wouldn’t be very notable - Asilisaurus is also that age - except that it is uncertain what to classify Nyasasaurus as. It is is known from a humerus and vertebrae, and cannot be confidently classified as a Dinosaur, or a Dinosauriform like Asilisaurus. If it is a Dinosaur, it pushes back the origin of Dinosaurs long before they were first thought to evolve - if it is not a Dinosaur, it is simply another piece in the puzzle that is the origin of this clade of animals - being as close to a dinosaur as one can get without actually being a dinosaur (ie, the sister animal to the group). 

By Jack Wood on @thewoodparable

If Nyasasaurus is a dinosaur, it would have predated all other known dinosaurs by about 10 to 15 million years. If it is a Dinosaur - and not just closely related to the ancestor of dinosaurs - then, when estimating the origin of dinosaurs, it is found that Dinosaurs were actually likely to have evolved in the Early Triassic, sometime between 252 and 247 million years ago, directly after the Permian Triassic extinction. This is much earlier than if Nyasasaurus is simply a sister taxon to Dinosaurs, where dinosaurs would have evolved in the Middle Triassic. It is even possible, if Nyasasaurus is a dinosaur, that Dinosaurs evolved in the Permian - right in the middle of the extinction, perhaps filling niches as they emptied rapidly. 

By Scott Reid on @drawingwithdinosaurs

At the very least, Nyasasaurus as a Dinosaur indicates that Dinosauromorphs - and, perhaps, Avemetatarsalians as a whole - evolved in the chaos of that extinction, filling niches and diversifying rapidly before the Paleozoic was even over. Given that Nyasasaurus was most recently found to be a Dinosaur, then it seems like this hypothesis is worth thorough consideration - though, of course, more complete remains of Nyasasaurus could change it back to being sister to Dinosaurs. 

Sources:

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

Lloyd, G. T., D. W. Bapst, M. Friedman, K. E. Davis. 2017. Probabilistic divergence time estimation without branch lengths: dating the origin of dinosaurs, avian flight and crown birds. Biology Letters 12: 20160609. 

Barown, M. G., D. B. Norman, P. M. Barrett. 2017. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 453: 501-506. 

By José Carlos Cortés on @quetzalcuetzpalin-art​

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Name: Silesaurus opolensis

Name Meaning: Silesia Reptile

First Described: 2003

Described By: Dzik

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Silesauridae

Silesaurus is the original Silesaurid - having lent its name to the group - and it comes from the Keuper Claystone in Silesia, Poland, living about 230 million years ago, in the Carnian age of the Late Triassic. As such, it was a relatively early Silesaurid, and in a different location than others in the group. It was also very large compared to other Silesaurids, about 2.3 meters long and mostly quadrupedal, though able to walk on two legs when needed. It was an herbivore, with small conical teeth, and a small beak at the front of its mouth. It was also a very derived Silesaurid, further lending credence to the idea that Dinosauromorphs evolved much earlier than previously believed. It moved upright, and rapidly, and was probably covered in filamentous integument - making it similar, but still distinct from, early dinosaurs. 

Source:

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

By Jack Wood on @thewoodparable

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Name: Pseudolagosuchus major

Name Meaning: False Lagosuchus

First Described: 1987

Described By: Arcucci

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Silesauridae

Pseudolagosuchus was a Silesaurid that is probably synonymous with Lewisuchus, but due to the lack of major overlapping material, this has only been hypothesized, rather than fully confirmed. It is from the Chañares Formation of Argentina, living in the Ladinian age of the Middle Triassic, about 236 to 234 million years ago. It was about 1 meter long and was one of the more early derived Silesaurids. 

Source:

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

By Scott Reid on @drawingwithdinosaurs

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Name: Sacisaurus agudoensis

Name Meaning: A Brazilian Creature with a Single Leg Reptile

First Described: 2010

Described By: Langer et al. 

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Silesauridae

Sacisaurus is a Silesaurid from the Caturrita Formation of Brazil, living about 225 million years ago, in the Norian age of the Late Triassic. It was 1.5 meters long and is known from portions of the leg, shoulder, tail, neck and skull. Originally thought to be an Ornithischian, it was since reassigned as a Silesaurid, and the fact that it shows adaptations for herbivory indicates that Silesaurids might have been herbivorous in general. It had strong legs and was probably a fast animal, which it would have needed to be to get away from predators in its environment. 

Source:

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

By Jack Wood on @thewoodparable

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Name: Ignotosaurus fragilis

Name Meaning: Unknown Reptile

First Described: 2013

Described By: Martínez et al. 

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Silesauridae

Ignotosaurus is a Silesaurid from the Ischigualasto Formation of Argentina, living about 231.4 million years ago, in the Carnian age of the Late Triassic. It is known from part of the leg bone, which indicates it was a small Silesaurid. This difference in leg bone probably indicates that it differed from other Silesaurids mainly in its method or needs during locomotion. It was closely related to Eucoelophysis, Silesaurus, and Sacisaurus, making it a fairly derived member of the Silesaurid group. Ignotosaurus lived in a complex community with many other species of reptiles, including early dinosaurs and other Archosauromorphs, such as Scaphonyx, Herrerasaurus, Proterochampsa, Chanaresuchus, Saurosuchus, Sillosuchus, Trialestes, Aetosauroides, Panphagia, Eoraptor, Chromogisaurus, Eodromaeus, and Sanjuansaurus. However, compared to, say, Herrerasaurus and Scaphonyx, or really, many others in this formation, it was relatively rare - indicating it was not a very common component of this ecology. 

Source:

Martínez, R. N.m C. Apaldetti, O. A. Alcober, C. E. Colombi, P. C. Sereno, E. Fernandez, P. S. Malnis, G. A. Correa, D. Abelin. 2013. Vertebrate succession in the Ischigualasto Formation. Journal of Vertebrate Paleontology 32 (sup1): 10-30. 

By José Carlos Cortés on @quetzalcuetzpalin-art​

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Name: Lutungutali sitwensis

Name Meaning: High Hip

First Described: 2013

Described By: Peecook et al. 

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Silesauridae

Lutungutali was a Silesaurid from the Ntawere Formation of Zambia, living in the Anisian age of the Middle Triassic, approximately 247 to 242 million years ago. It is one of the oldest known Avemetatarsalians (along with Asilisaurus), and is known from parts of the pelvis and tail vertebrae. Its main difference from other Silesaurids was that it had a higher hip than other Silesaurids and Dinosauriformes - which lent to its name. This could indicate that its posture, movement, and niche was different than other Silesaurids, leading to it needing to have high hips. It was a fairly derived Silesaurid, as well, though furthering the hypothesis that Dinosauromorphs evolved much earlier than previously supposed, undergoing a rapid diversification around the time of the Permian-Triassic extinction. 

Source:

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

By Jack Wood on @thewoodparable

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Name: Asilisaurus kongwe

Name Meaning: Ancestor Reptile

First Described: 2010

Described By: Nesbitt et al. 

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Silesauridae

Asilisaurus is our first Silesaurid, and one of my absolute favorite reptiles out there. Silesaurids were a group of Dinosauriformes very closely related to Dinosaurs, a quite diverse group of lightly built animals that were actually mostly quadrupedal. They might have also been herbivorous, with at least one genus being so - Sacisaurus. Asilisaurus itself is specifically fascinating because of its age: it is about 245 million years old, from the Anisian age of the Middle Triassic. This age pushes back the origin of Dinosauromorphs much farther than it had previously been - it is the oldest known member of the group, and yet, fairly derived for it (and even at least somewhat derived as a Silesaurid), indicating that Dinosauromorphs evolved much earlier than previously supposed, perhaps even right at the Permian-Triassic boundary, as part of a rapid radiation of animals following that catastrophic extinction event (and it is even possible that Dinosauromorphs might be even older- but more on that when we get to Nyasasaurus). Asilisaurus itself was from the Manda Formation of Tanzania, one of the most interesting formations being studied right now, showing important information on the origin of these reptiles. It was about 1 to 3 meters long, fairly active, potentially quadrupedal, and probably covered in filamentous integument. 

Source:

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