#dinosauromorph

[a-dinosaur-a-day]

I have made a thing

yep, it includes all birds and no pterosaurs. I say Dinosauromorph, after all.

[edgescience]

A newly described proto-dino-pterosaur provides new insights into the evolution of both dinosaurs and pterosaurs.

[i-draws-dinosaurs]

Okayyyy, back to posting art on here!! It’s been a while, but here’s the first piece that I created for @wtf-triassic​, the tiny boi dinosauromorph Lagerpeton chanarensis. This small lad hails from the Argentinian Chañares Formation, and is about 235ma old. As a dinosauromorph, Lagerpeton falls just outside the line between dinosaur and non-dinosaur, which is a super abitrary line given how similar some of these species are to “true” dinosaurs. The Chañares Formation is full of other almost-dinosaurs-but-not-quite, making it a fascinating snapshot in time of the very beginnings of the dinosaurian lineage.

As an almost-a-dinosaur, Lagerpeton was probably covered in fluffy filaments, or “protofeathers”, since based on their existence in both dinosaurs and pterosaurs these fibres were likely ancestral at least to ornithodirans, the group that includes pterosaurs, dinosaurs, and vague difficult-to-define little things like Lagerpeton.

There’s not a whole lot special about this reconstruction in particular, I used my usual process for digital painting. I did make more use of textured brushes, which are an excellent way of roughing out textures that I highly recommend experimenting with. I might make a tutorial post on that at some point, it’s something I’ve found extremely useful.

I also chose to make him spotty, since for some reason there aren’t many reconstructions of spotty dinosaurs even though spots are everywhere in the animal kingdom. #bringbackspotsinpalaeoart2020 guys, let’s get that disgustingly-clunky tag trending.

[apsaravis]

Tarjadia and Marasuchus.

Photoshop

[typhlonectes]

New Proto-Dinosaur Found in Colorado

A lanky reptile found in the Centennial State is a close cousin of early dinosaurs

What’s almost a dinosaur, but not quite? The answer, as paleontologists have come to understand, is “a silesaur!”, a non-dinosaurian dinosauromorph. I know that’s a bit of a mouthful. Let’s unpack that.

Silesaurs aren’t exactly famous in fossil circles yet. The iconic member of the group, Silesaurus, was named in 2003 and the group’s identity wasn’t fully recognized until 2010. As old as they are, dating back through the Middle and Late parts of the Triassic, they’re pretty new on the Mesozoic block. And they’re important to our understanding of how dinosaurs evolved. Silesaurs are not technically dinosaurs, but they’re close relatives that belong to the larger group which dinosaurs are nested in.

That’s why they’re called non-dinosaurian dinosauromorphs – in short, protodinos. And paleontologists Jeffrey Martz and Bryan Small have just named a new one from Colorado.

The new silesaur, known from parts of the skull and body, is named Kwanasaurus williamparkeri and lived more than 207 million years ago. Its name is a combination of Ute and Greek meaning “eagle lizard,” while the species name honors influential Triassic paleontologist Bill Parker. It’s the fourth silesaur known from North America, and the latest of 11 described so far...

Read more: https://blogs.scientificamerican.com/laelaps/new-proto-dinosaur-found-in-colorado/

[perpetualartistsblock]

Day 9 of my palette challenge (palettes found here) has the carnivorous sauropodomorph Buriolestes in #29, snatching up an unlucky Ixalerpeton.

[rmyers08]

Dinovember ... #drawdinovember #dinosauromorph #dinosaur #arboreal #triassic #ink #doodle #paleoart #artistsoninstagram https://www.instagram.com/p/BqEHZknF8Ts/?utm_source=ig_tumblr_share&igshid=rpcfync81ii3

[nightjarwhiskers]

Sometimes you just gotta take a moment to behold your gloriously fluffy tail...

This animal is a lagerpetid, a dinosauromorph that lived in the late Triassic! They were pretty small and very skilled at hopping around everywhere.

Instagram

[dinosaurs-dinosaurs-dinosaurs]

Silesaurus by FunkMonk, in the public domain. Retrieved from Wikipedia. 

[a-dinosaur-a-day]

Silesaurus opolensis

By José Carlos Cortés

Etymology: Silesian Reptile

First Described By: Dzik, 2003 

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Silesauridae, Sulcimentisauria  

Time and Place: Around 230 million years ago, in the Carnian of the Late Triassic

Silesaurus is known from the Drawno Beds Formation of Poland

Physical Description: Silesaurus was a very common almost-dinosaur - specifically, the titular member of the Silesaurids - from Poland in the middle of the Triassic period. It was a quadrupedal animal, about 2.3 meters long and small enough that it most likely would have been covered in fluff. Like other Silesaurids, it was long - with a long neck and a long tail, and long limbs easily reaching to the ground. Like other Silesaurids, it almost had its legs directly underneath its body - it didn’t seem to have an open acetabulum, but rather a partially open one, though Silesaurids are something of a confusing case on this regard. It had a small head, with a little beak in the front, and small sharp conical teeth. In addition, it had very large eyes, giving it distinctly good eyesight, as well as a decent sense of smell. As a quadruped, its front limbs were rather extended, while the hind limbs did a lot of the weight support. 

Diet: Interestingly enough, though for a long time it was thought that Silesaurus was an herbivore, recent fossil poop studies have indicated it was an insectivore - similar to living birds.

By Ripley Cook

Behavior: If Silesaurus really was an insectivore, it would have spent much of its time moving around in its environment, examining it closely for insects and pecking at the ground with its small beak for food. This pecking may have even looked a lot like that of living birds - the large eyes probably would have prevented the eyes from moving much, like in living birds, and as such Silesaurus would have had to bob its head in order to see. It  would have been very careful in its environment, making sure to look for food and avoid predatory dangers in its environment. It would probably have been social - corroborated by the fact that it was very common in its environment - and taken care of its young to some extent. As an Archosaur, it would have been warm blooded as well, and very active. 

Ecosystem: Silesaurus lived in a Mediterranean-esque scrub environment, with summer monsoon seasons and dry winters. The swampy coniferous forest and fernlands it lived in had a wide variety of animals, placing Silesaurus in a unique ecosystem of the Carnian age. This is actually quite important, given that the Carnian Pluvial Event - a minor mass extinction that helped to spur Dinosaurian evolution - occurred around the same time, leading to Silesaurus and its contemporaries being a snapshot of this change. A variety of invertebrates lived alongside this animal, giving it plenty of food, as well as Temnospondyls such as Metoposaurus and Cyclotosaurus, the Aetosaur Stagonolepis, the Phytosaur Parasuchus, the Rauisuchid Polonosuchus, the Sharovpterygid Ozimek, and probably some Tuataras and maybe even a Pterosaur. A small community, but a beautiful portrait of this time period, with its fair share of weirdos and precursors. And Silesaurus would have had a lot to look out for with Polonosuchus at just the right size to attack it. 

Other: Do not let Silesaurus’s weird similarities to birds fool you - it wasn’t an early bird, but a showcase of how bird-like traits kept popping up over and over again in the line of animals leading up to them. In fact, the evolution of such a specialized feeding system is notable in such an early member of the Ornithodirans. Silesaurids in general are extremely interesting because of their mixture of characters - similar to dinosaurs, but not quite there; with legs almost directly underneath the body, but other traits that match the later Ornithischians. The problem with Ornithischians - the bird-hipped dinosaurs - is that they have a bit of a ghost lineage, aka even though they should have showed up at the same time as Theropods and Sauropodomorphs, they don’t until the Early Jurassic. This isn’t as big of a gap as some other examples, but it is notable. Silesaurids have come out as Ornithischians just enough times in phylogenetic studies to bring it up as a question - are they almost-dinosaurs? The first bird-hips (without having bird-hips)? Something else entirely? More research is necessarily, but one thing is for sure - this group of weird dinosaurian experiments is one to keep an eye on, especially as we learn more and more about them. 

~ By Meig Dickson

Sources Under the Cut

Cau, A. 2018. The assembly of the avian body plan: a 160-million-year long process. Bollettino della Società Paleontologica Italiana 57 (1): 1 - 25. 

Dzik, J. 2003. A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland. Journal of Vertebrate Paleontology 23(3):556-574. 

Dzik, J. and T. Sulej. 2007. A review of the early Late Triassic Krasiejów biota from Silesia, Poland. Palaeontologia Polonica 64:3-27. 

Ezcurra, M. D. 2006. A review of the systematic position of the dinosauriform archosaur Eucoelophysis baldwini Sullivan & Lucas, 1999 from the Upper Triassic of New Mexico, USA. Geodiversitas 28(4):649-684. 

Griffin, C. T., and S. J. Nesbitt. 2016. The femoral ontogeny and long bone histology of the Middle Triassic (?late Anisian) dinosauriform Asilisaurus kongwe and implications for the growth of early dinosaurs. Journal of Vertebrate Paleontology 36(3):e1111224:1-22. 

Irmis, R. B., S. J. Nesbitt, K. Padian, N. D. Smith, A. H. Turner, D. T. Woody, and A. Downs. 2007. A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs. Science 317:358-361. 

Jagt, J. W. M., G. Hebda, S. Mitrus, E. Jagt-Yazykov, A. Bodzioch, D. Konietzko-Meier, K. Kardynał, K. Gruntmejer. 2015. Field Guide, Conference Paper, European Association of Vertebrate Palaeontologists XIII Annual Meeting. 

Kammerer, C. F., S. J. Nesbitt, and N. H. Shubin. 2012. The first basal dinosauriform (Silesauridae) from the Late Triassic of Morocco. Acta Palaeontologica Polonica 57(2):277-284. 

Langer, M. C., M. D. Ezcurra, J. S. Bittencourt and F. E. Novas. 2010. The origin and early evolution of dinosaurs. Biological Reviews 85:55-110. 

Martínez, R. N., and O. A. Alcober. 2009. A basal sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the early evolution of Sauropodomorpha. PLoS ONE 4(2 (e4397)):1-12. 

Martz, J. W., and B. J. Small. 2019. Non-dinosaurian dinosauromorphs from the Chinle Formation (Upper Triassic) of the Eagle Basin, northern Colorado: Dromomeron romeri (Lagerpetidae) and a new taxon, Kwanasaurus williamparkeri (Silesauridae). PeerJ 7:e7551:1-71. 

Nesbitt, S. J., C. A. Sidor, R. B. Irmis, K. D. Angielczyk, R. M. H. Smith and L. A. Tsuji. 2010. Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira. Nature 464:95-98. 

Nesbitt, S. J. 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 353:1-292. 

Qvarnström, M., J. V. Wernström, R. Piechowski, M. Tałanda, P. E. Ahiberg, G. Niedźwiedzki. 2019. Beetle-bearing coprolites possibly reveal the diet of a Late Triassic dinosauriform. Royal Society Open Science 6 (3): 181042. 

[a-dinosaur-a-day]

Pisanosaurus mertii

By José Carlos Cortés 

Etymology: Pisano’s Reptile

First Described By: Casamiquela, 1967

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Silesauridae?

Status: Extinct

Time and Place: 231.4 million years ago, in the Carnian of the Late Triassic 

Pisanosaurus is known from the Cancha de Bochas Member of the Ischigualasto Formation in San Juan Argentina. 

Physical Description: If a Silesaurid - as is currently thought - Pisanosaurus would have been a small, slender, and quadrupedal animal, only about 1 meter in length. It had an open hip socket, like dinosaurs, which may point to a very interesting phylogenetic position (see the Other section below). It had very elongated bones in its hands, and its upper hips were weirdly wide as well. Beyond that, we don’t know much about with Pisanosaurus may have looked like. It seems logical to suppose it would have had a small head with a little beak in the front of the mouth - as both Silesaurids and early Ornithischians (the other hypothesis for the type of creature Pisanosaurus was) have such structures for snipping off plant material. Given its small size, Pisanosaurus - like all other early members of the group of reptiles that would later include birds (Avemetatarsalia) - would have been covered with fluff all over its body. If Pisanosaurus was an early Ornithischian and not a Silesaurid, it would have been bipedal, with short forelimbs not used in locomotion.

Diet: Either way, Pisanosaurus would have been an herbivore, eating low-lying vegetation in its densely forested home.

Behavior: As a small, lithe herbivore, Pisanosaurus would have been very skittish - running at the slightest sign of danger, making sure to avoid the many large predators it shared a home with. It probably wouldn’t have been very social - given it wasn’t very abundant! - but it may have foraged in large groups of mixed herbivores, sticking together to rely on each other in the event of danger. This reliance would have allowed bulkier herbivores to notice and react to danger quicker (since the small lithe ones like Pisanosaurus would have already been running away) - and the smaller ones would have had large, bulky roadblocks to stop the approach of predators. As an early dinosaur, it most likely partook in some sort of care of its young, though of course, we do not know what. 

(As an Ornithischian) by Michael B. H., CC BY-SA 3.0 

Ecosystem: The Ischigualasto Environment is one of the more famous ecosystems of the Late Triassic - due to it being a hotbed of early dinosaur discoveries, including some of the earliest potential members of the group. In fact, it is such an important environment that today the rock formation is considered a UNESCO World Heritage Site. It was an extensive series of rivers channeling through a large floodplain, erring towards the wetter side of the scale - mud was the name of the game, and there was a wide variety of plant material present, including a dense conifer forest, ferns, and horsetails. It did experience seasonal rainfall, with possible times of extremely heavy precipitation. Occasionally, everything would be buried in volcanic ash - leading to the beautiful preservation of the environment.

Pisanosaurus wasn’t the only Silesaurid here - there was also Ignotosaurus, the slender and small Silesaurid. There were also famous early dinosaurs such as Eoraptor - the small, bipedal early Saurischian(?), Herrerasaurus and Sanjuansaurus, the large taxonomically-confusing predators, and Chromogisaurus, one of the earliest known “prosauropods.” Of course, this being the Triassic, dinosaurs were only a small part of the ecosystem. The Ischigualasto - like most places of the time period - was absolutely lousy with other archosauriformes! Non-Dinosaurian Archosauriformes were extensively diverse at this time, making up a large chunk of the “large charismatic land animal” roles. There was Aetosauroides, an Aetosaur (sort of like a cross between an ankylosaur, an ant-eater, and a crocodile), Proterochampsa and Pseudochampsa - crocodilian-like creatures that were actually equally closely related to crocodiles and dinosaurs - both frequented the rivers of the environment. Saurosuchus, a large and bulky stem-croc, would have been a huge pain in the rear for herbivores like Pisanosaurus. Sillosuchus was a weird stem-croc, bipedal and strangely dinosaur like - with even, potentially, a beak - but utterly scaly, and bulky in stature! There was also Venaticosuchus, an Ornithosuchid (one of the most basal groups of stem-crocs), and Trialestes - a fast moving stem-croc, and one of the earliest Crocodylomorphs (the group of crocodilians and their closest relatives). 

(Without Feathers) by Nobu Tamura, CC BY-SA 4.0 

It being the Triassic, this wasn’t an environment free of non-reptiles! Temnospondyls - large carnivorous amphibians - were crawling about; as were a variety of Synapsids. Small, carnivorous dog-shaped cynodonts like Chiniquodon would have directly competed with the local dinosaurs; they even grew to be quite large and fast, like in Diegocanis and Ecteninion. They also came in large, bulky herbivorous forms, like Exaeretodon. Dicynodonts were present too, with their strange pig-like appearance: Ischigualastia was a common synapsid on the floodplains of Pisanosaurus’ home. In short, Pisanosaurus was surrounded with a cast of characters showcasing some - but certainly not all - of the weirdness that the Triassic  had to offer.

Other: What Is Pisanosaurus? Back in the day, Pisanosaurus was a famous creature for being one of the earliest “Ornithischian” dinosaurs - one of two major groups of dinosaurs, famous for including such later iconic members as Stegosaurus and Triceratops. In fact, for the longest time, Pisanosaurus was… the only Ornithischian known from the Triassic. This is odd, to say the least - there are dozens of Triassic dinosaurs known, they’re just all from the other group, the Saurischians (containing such iconic later forms as Apatosaurus, Tyrannosaurus, and… all birds). So, for the longest time, Pisanosaurus stood as a focal point of dinosaur research - an important piece of the puzzle of the origin of this elusive, but important group. 

By Nix 

Except it isn’t an Ornithischian. Lately, studies have shown time and time again that Pisanosaurus actually more closely resembles the Silesaurids - a group of almost dinosaurs that were quadrupedal, active herbivores living around the world at the time of the Triassic, before going extinct at the end-Triassic extinction. This would make its appearance much different than what a “basal Ornithischian” would suggest - and, of course, the fact that Pisanosaurus is known from only a single fragmented skeleton does not make solving this problem much easier. Weirdly enough, there are some hypotheses which suggest that Silesaurids are… the earliest Ornithischians, (as per Pisanosaurus having an open hip-socket), representing a weird side-branch of the group from the Triassic. As this hypothesis gains traction, it may become increasingly true that Pisanosaurus was a Silesaurid - it was just also an early Ornithischian. Only time will tell in the solving of this mystery - for now, we must wait for more evidence.

~ By Meig Dickson

Sources Under the Cut 

Abdala, F. 2000. Catalogue of non-mammalian cynodonts in the Vertebrate Paleontology Collection of the Instituto Miguel Lillo, Universidad Nacional de Tucuman, with comments on species. Ameghiniana 37(4):463-475

Aceituno Cieri, P.; M.E. Zeballos; R.J. Rocca; R.D. Martino, and C. Carignano. 2015. Condicionantes geológicos en el cruce de la sierra de Valle Fértil. San Juan - Geological constraints at the crossing of sierra Valle Fertil. San Juan. Revista de Geología Aplicada a la Ingeniería y al Ambiente 35. 57–69.

Agnolin, F. L., (2015). "Nuevas observaciones sobre Pisanosaurus mertii Casamiquela, 1967 (Dinosauriformes) y sus implicancias taxonómicas". XXIX Jornadas Argentinas de Paleontología de Vertebrados. 27–29 de Mayo de 2015. Diamante, Entre Ríos. Libro de Resúmenes: 13–14.

Agnolín, Federico L.; Rozadilla, Sebastián (2017). "Phylogenetic reassessment of Pisanosaurus mertii Casamiquela, 1967, a basal dinosauriform from the Late Triassic of Argentina". Journal of Systematic Palaeontology. 16 (10): 853–879.

Alcober, Oscar A., and Ricardo N. Martínez. 2010. A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina. ZooKeys 63. 55–81.

Alcober, Oscar A., and J. Parrish. 2010. A new poposaurid from the Upper Triassic of Argentina. Journal of Vertebrate Paleontology 17. 548–556.

Anderson, J. M., and A. R. I. Cruickshank. 1978. The biostratigraphy of the Permian and the Triassic. Part 5. A review of the classification and distribution of Permo-Triassic tetrapods. Palaeontologica Africana 21:15-44.

Balabusic, Ana M., et al. 2001. Plan de Manejo del Parque Nacional Talampaya, 1–68. Administración de Parques Nacionales.

Bakker, R. T., and P. M. Galton. 1974. Dinosaur monophyly and a new class of vertebrates. Nature 248:168-172.

Bonaparte, J. F. 1969. Comments on early saurischians. Zoological Journal of the Linnean Society 48:471-480.

Bonaparte, J.F. (1970). "Annotated list of the South American Triassic tetrapods". Gondwana Symposium Proceedings and Papers. 2: 665–682.

Bonaparte, J. F. 1973. Edades reptil para el Triásico de Argentina y Brasil [Reptila ages for the Triassic of Argentina and Brazil]. Quinto Congreso Geológico Argentino, Ciudad de Villa Carlos Paz. Actas 3:93-129.

Bonaparte, J. F. 1976. "Pisanosaurus mertii Casamiquela and the origin of the Ornithischia". Journal of Paleontology 50(5): 808-820  

Bonaparte, J. F. 1978. El Mesozoico de America de Sur y sus Tetrapodos [The Mesozoic of South America and its tetrapods]. Opera Lilloana 26:1-596.

Bonaparte, J. F. 1984. I dinosauri dell’Argentina [. In G. M. Ronzoni, M. L. Greggio, & T. B. Guarinoni (eds.), Sulle Orme dei Dinosauri 125-143.

Butler, R. J., R. M. H. Smith, and D. B. Norman. 2007. A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia. Proceedings of the Royal Society of London B 274:2041-2046.

Butler, Richard J.; Upchurch, Paul and Norman; David, B. (2008). "The phylogeny of the ornithischian dinosaurs". Journal of Systematic Palaeontology. 6 (1): 1–40.  

Cabrera, Ángel. 1943. El primer hallazgo de terápsidos en la Argentina. Notas del Museo de la Plata 8. 317–331.

Cabreira, Sergio F.; Cesar L. Schultz; Jonathas S. Bittencourt; Marina B. Soares; Daniel C. Fortier; Lúcio R. Silva, and Max C. Langer. 2011. New stem-sauropodomorph (Dinosauria, Saurischia) from the Triassic of Brazil. Naturwissenschaften 98. 1035–1040.

Carroll, R. L. 1988. Vertebrate Paleontology and Evolution 1-698.

Casamiquela, R. M. 1967. Un nuevo dinosaurio ornitisquio triasico (Pisanosaurus mertii; Ornithopoda) de la Formación Ischigualasto, Argentina [A new Triassic ornithischian dinosaur (Pisanosaurus mertii; Ornithopoda) from the Ischigualasto Formation, Argentina]. Ameghiniana 4(2):47-64.

Colbert, E. H. 1981. A primitive ornithischian dinosaur from the Kayenta Formation of Arizona. Museum of Northern Arizona Bulletin 53:1-61.

Columbi, Carina E. (2008-10-05). Stable isotope analysis of fossil plants from the Upper Triassic Ischigualasto Formation in the northwest of Argentina. Houston, TX: The Geological Society of America.

Contreras, V. H. 1981. Datos preliminares sobre un nuevo rincosaurio (Reptilia, Rhynchosauria) del Triasico Superior de Argentina. Anais II Congresso Latino-Americano Paleontologia, Porto Alegre 2:289-294

Cox, C. B. 1965. New Triassic dicynodonts from South America, their origins and relationships. Philosophical Transactions of the Royal Society of London, Series B 248(753):457-516

Ezcurra, Martín D. 2010. A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny. Journal of Systematic Palaeontology 8. 371–425.

Ezcurra, M. D., R. N. Martínez. 2016. Dinosaur precursors and early dinosaurs from Argentina. Book: Historia Evolutiva y Paleobiogeografía de los Vertebrados de América del Sur, Publisher: Contribuciones del MACN, Editors: F. Agnolíin, GL Lio, F. Brissón Egli, NR Chimento, F. Novas, 97-107.

Godefroit, P., S. M. Sinitsa, D. Dhouailly, Y. L. Bolotsky, A. V. Sizov, M. E. McNamara, M. J. Benton and O. Spagna. 2014. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales. Science 345(6):451-455

Hollocher, K.T.; O.A. Alcober; C.E. Colombi, and T.C. Hollocher. 2005. Carnivore coprolites from the Upper Triassic Ischigualasto Formation, Argentina: chemistry, mineralogy, and evidence for rapid initial mineralization. Palaios 20. 51–63.

Irmis, R.B.; Parker, W.G.; Nesbitt, S.J.; Liu, J. (2007). "Early ornithischian dinosaurs: the Triassic record". Historical Biology. 19: 3–22.

Irmis, R. B., and F. Knoll. 2008. New ornithischian dinosaur material from the Lower Jurassic Lufeng Formation of China. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 247(1):117-128

Langer, M. C., and M. J. Benton. 2006. Early dinosaurs: a phylogenetic study. Journal of Systematic Palaeontology 4(4):309-358

Langer, M. C., Ezurra, M. D., Bittencourt, J. S., and Novas, F. E., 2009. The origin and early evolution of dinosaurs: Biological Reviews, v. 84, p. 1-56

Langer, Max C.; Sterling J. Nesbitt; Jonathas S. Bittencourt, and Randall B. Irmis. 2013. Anatomy, phylogeny and palaeobiology of early archosaurs and their kin. Geological Society, London, Special Publications 379. 157–186.

Lecuona, A.; M.D. Ezcurra, and R.B. Irmis. 2016. Revision of the early crocodylomorph Trialestes romeri (Archosauria, Suchia) from the lower Upper Triassic Ischigualasto Formation of Argentina: one of the oldest-known crocodylomorphs. Papers in Palaeontology 2. 585–622.

Lovelace, D., S. Hartman, B. J. Linzmeier, W. P. Porter. 2018. Deep-Time Application of Linked Microclimate and Biophysical Models Constrain the Thermal Ecology of Two Late Triassic Dinosaurs (Coelophysis, Plateosaurus). Journal of Vertebrate Paleontology Abstract Book: 171.

Madzia, D., C. A. Boyd, and M. Mazuch. 2018. A basal ornithopod dinosaur from the Cenomanian of the Czech Republic. Journal of Systematic Palaeontology 16(11):967-979

Marsola, J. C. A., J. S. Bittencourt, R. J. Butler, A. S. Da Rosa, J. M. Sayão, M. C. Langer. 2019. A new dinosaur with theropod affinities from the Late Triassic Santa Maria Formation, South Brazil. Journal of Vertebrate Paleontology: e1531878.

Martínez, R.N., and C.A. Forster. 1996. The skull of Probelesodon sanjuanensis, sp. nov., from the Late Triassic Ischigualasto Formation of Argentina. Journal of Vertebrate Paleontology 16. 285–291.

Martínez, Ricardo N., and Oscar A. Alcober. 2009. A Basal Sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the Early Evolution of Sauropodomorpha. PLoS ONE 4. 1–12.

Martínez, Ricardo N.; Paul C. Sereno; Oscar A. Alcober; Carina E. Colombi; Paul R. Renne; Isabel P. Montañez, and Brian S. Currie. 2011. A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea. Science 331. 206–210.

Martínez, Ricardo N.; Eliana Fernández, and Oscar A. Alcober. 2013. A new non-mammaliaform eucynodont from the Carnian-Norian Ischigualasto Formation, Northwestern Argentina. Revista Brasileira de Paleontologia 16. 61–76.

Martínez, Ricardo N.; Cecilia Apaldetti; Oscar A. Alcober; Carina E. Colombi; Paul C. Sereno; Eliana Fernández; Paula Santi Malnis; Gustavo A. Correa, and Diego Abelin. 2013. Vertebrate succession in the Ischigualasto Formation. Journal of Vertebrate Paleontology Memoir 12: Basal sauropodomorphs and the vertebrate fossil record of the Ischigualasto Formation (Late Triassic: Carnian-Norian) of Argentina. 10–30.

Monetta, A.; J. Baraldo; A. Cardinali; R. Weidmann, and M. Lanzilotti. 2000. Distribución y características del magmatismo intratriasico de Ischigualasto, San Juan, Argentina, 644–648. IX Congreso Geológico Chileno.  

Müller, R. T., S. Dias-da-Silva. 2017. Taxon sample and character coding deeply impact unstable branches in phylogenetic trees of dinosaurs. Historical Biology 21 (8): 1-4.

Norman, D. B., L. M. Witmer, and D. B. Weishampel. 2004. Basal Ornithischia. In D. B. Weishampel, H. Osmolska, and P. Dodson (eds.), The Dinosauria (2nd edition). University of California Press, Berkeley 325-334

Novas, F. E. 1986. Un probable teropodo (Saurischia) de la Formacion Ischigualasto (Triasico Superior), San Juan, Argentina [A probable theropod (Saurischia) from the Ischigualasto Formation (Upper Triassic), San Juan, Argentina]. IV Congreso Argentino de Paleontologia y Bioestratigrafia 1:1-6

Reig, O. A. 1963. La presencia de dinosaurios saurisquios en los "Estratos de Ischigualasto" (Mesotriasico Superior) de las provincias de San Juan y La Rioja (República Argentina) [The presence of saurischian dinosaurs in the "Ischigualasto beds" (upper Middle Triassic) of San Juan and La Rioja Provinces (Argentine Republic)]. Ameghiniana 3(1):3-20

Rogers, R. R.; Swisher III, C.C.; Sereno, P.C.; Monetta, A.M.; Forster, C.A.; Martinez, R.N. (1993). "The Ischigualasto tetrapod assemblage (Late Triassic, Argentina) and 40Ar/39Ar dating of dinosaur origins". Science. 260 (5109): 794–797.  

Schencman, Laura Jazmín; Carina Colombi; Paula Santi Malnis, and Carlos Oscar Limarino. 2015. Diagenesis and provenance of the Los Colorados formation (Norian), Ischigualasto- Villa Unión basin, Northwest of Argentina. Revista de la Asociación Geológica Argentina 72. 219–234.

Sereno, P.C. (1991). "Lesothosaurus, "fabrosaurids", and the early evolution of Ornithischia". Journal of Vertebrate Paleontology. 11 (2): 168–197.

Sereno, P.C.; Novas, F.E. (1992). "The complete skull and skeleton of an early dinosaur". Science. 258 (5085): 1137–1140.

Sereno, P. C. 1999. The evolution of dinosaurs. Science 284:2137-2147

Trotteyn, María J.; Ricardo N. Martínez, and Oscar A. Alcober. 2012. A new proterochampsid Chanaresuchus ischigualastensis (Diapsida, Archosauriformes) in the early Late Triassic Ischigualasto Formation, Argentina. Journal of Vertebrate Paleontology 32. 485–489.

Trotteyn, María Jimena, and Martín D. Ezcurra. 2014. Osteology of Pseudochampsa ischigualastensis gen. et comb. nov. (Archosauriformes: Proterochampsidae) from the Early Late Triassic Ischigualasto Formation of Northwestern Argentina. PLoS ONE 9. 1–37.

Tucker, Maurice E.; Benton, Michael J. (1982). "Triassic environments, climates, and reptile evolution". Palaeogeography, Palaeoclimatology, Palaeoecology. 40 (4): 361–379.

Wallace, Rachel Veronica Simon. 2018. A new close mammal relative and the origin and evolution of the mammalian central nervous system (PhD thesis), 1–224. The University of Texas at Austin.

Yang, Z., B. Jiang, M. E. McNamara, S. L. Kearns, M. Pittman, T. G. Kaye, P. J. Orr, X. Xu., M. J. Benton. 2018. Pterosaur integumentary structures with complex feather-like branching. Nature Ecology & Evolution 3: 24 - 30.

[a-dinosaur-a-day]

Lagosuchus talampayensis

By José Carlos Cortés 

Etymology: Rabbit Crocodile

First Described By: Romer, 1971

Classification: Dinosauromorpha

Status: Extinct

Time and Place: About 238 million years ago, in the Ladinian age of the Middle Triassic 

Lagosuchus is found in the Chañares Formation of Argentina 

Physical Description: Lagosuchus was an early Dinosauromorph, aka the group that includes dinosaurs and all their closest relatives. Thus, Lagosuchus is one of many early archosaurs that showcase the origins of all dinosaurs! Lagosuchus isn’t known from particularly good remains, but it does show it was a lightly built, agile animal, which was probably bipedal and spent most of its times on its toes. At about 30 centimeters in length, it was around the size of a ferret. Its legs were amazingly long, and its toes were too, giving it good speed. It had an almost-erect posture - without the open hip sockets of dinosaurs proper, it couldn’t hold its legs directly underneath its body, but it almost could. Its forelimbs are a bit more murky, though it seems likely that Lagosuchus moved on all fours most of the time, switching to two legs when it needed to move quickly from place to place. Being an early dinosauromorph, it would have had some covering of protofeathers, though how much is a bit of question.

Diet: Lagosuchus was probably an omnivore, given the fact that early dinosaurs probably came from omnivorous origins

Behavior: Lagosuchus would have been a moderately active animal - close to a warm-blooded metabolism but not quite. As such, it probably would have spent most of its time on the move, hunting for food or searching for grubs and possibly plants it could have eaten. Lagosuchus could have used its speed to run away from predators, which were very common in its environment; and, of course, running after its own food!

It is uncertain if Lagosuchus was a social animal, or if it took care of its young; but it seems likely for the latter at least. 

By Ripley Cook 

Ecosystem: The Chañares Formation was a middle triassic microcosm of the explosion of evolution occurring in the Triassic, showcasing a wide variety of animals evolving in the aftermath of the Permian mass extinction. This was a low lying lake system, filled with horsetails, ferns, and some nearby conifer trees. It was also very warm, though not as warm as locations closer to the equator. There were many kinds of animals - large predatory pseudosuchians that would have hunted Lagosuchus such as Gracilisuchus, Luperosuchus, and Tarjadia; other Avemetatarsalians such as Marasuchus, Pseudolagosuchus, Lewisuchus, and Lagerpeton; the carnivorous almost-mammals Probainoganthus and Chiniquodon; the herbivorous almost-mammal Massetognathus; giant Dicynodont herbivores like Dinodontosaurus and Jachaleria; and finally the vaguely-crocodile-like Proterochampsids Gualosuchus, Chanaresuchus, and Tropidosuchus. A fascinating community indeed!

Other: Lagosuchus isn’t a particularly well known dinosauromorph; fossils assigned to it at one point that are well known, Marasuchus, have been given their own genus. It is possible that Lagosuchus is, thus, closer to dinosaurs in relationship than we think just on its own without evidence from Marasuchus. More studying of these fossils is necessary to come to better conclusions.

~ By Meig Dickson

Sources under the Cut 

Arcucci, A.B. 1987. Un nuevo Lagosuchidae (Thecodontia-Pseudosuchia) de la fauna de Los Chañares (Edad Reptil Chañarense, Triasico Medio), La Rioja, Argentina. Ameghiniana 24. 89–94.

Arcucci, A., and C.A. Marsicano. 1999. A distinctive new archosaur from the Middle Triassic (Los Chañares Formation) of Argentina. Journal of Vertebrate Paleontology 19. 228–232.

Bittencourt, Jonathas S.; Andrea B. Arcucci; Claudia A. Marsicano, and Max C. Langer. 2014. Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs. Journal of Systematic Palaeontology _. 1–31.

Fiorelli, Lucas E.; Sebastián Rocher; Agustín G. Martinelli; Martín D. Ezcurra; E. Martín Hechenleitner, and Miguel Ezpeleta. 2018. Tetrapod burrows from the Middle–Upper Triassic Chañares Formation (La Rioja, Argentina) and its palaeoecological implications. Palaeogeography, Palaeoclimatology, Palaeoecology 496. 85–102.

Jose, B. 1975. "Nuevos materiales de Lagosuchus talampayensis Romer (Thecodontia-Pseudosuchia) y su significado en el origen de los Saurischia: Chañarense inferior, Triásico medio de Argentina." Acta Geológica Lilloana. 13 (1): 5–90.

Kent, Dennis V.; Paula Santi Malnis; Carina E. Colombi; Oscar A. Alcober, and Ricardo N. Martínez. 2014. Age constraints on the dispersal of dinosaurs in the Late Triassic from magnetochronology of the Los Colorados Formation (Argentina). Proceedings of the National Academy of Sciences 111. 7958–7963.

Marsicano, C. A., R. B. Irmis, A. C. Mancuso, R. Mundil, F. Chemale. 2016. "The precise temporal calibration of dinosaur origins". Proceedings of the National Academy of Sciences of the United States of America. 113 (3): 509–513.

Nesbitt, S.J. 2011. "The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades" (PDF). Bulletin of the American Museum of Natural History. 352: 189.

Romer, A. S. 1971. "The Chañares (Argentina) Triassic reptile fauna. X. Two new but incompletely known long-limbed pseudosuchians". Breviora. 378: 1–10.

Romer, A. S. 1972. "The Chañares (Argentina) Triassic reptile fauna. XV. Further remains of the thecodonts Lagerpeton and Lagosuchus". Breviora. 394: 1–7.

Palmer, D., ed. 1999. The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 97.

Paul, G. 1988. Predatory Dinosaurs of the World. Simon & Schuster.

Perez Loinaze, V. S., E. I. Vera, L. E. Fiorelli, J. B. Desojo. 2018. Palaeobotany and palynology of coprolites from the Late Triassic Chañares Formation of Argentina: implications for vegetation provinces and the diet of dicynodonts. Palaeogeography, Palaeoclimatology, Palaeoecology 502: 31 - 51.

Pontzer, H., V. Allen, J. R. Hutchinson. 2009. "Biomechanics of Running Indicates Endothermy in Bipedal Dinosaurs". PLoS ONE. 4 (12): e7783.

Rogers, R.R.; A.B. Arcucci; F. Abdala; P.C. Sereno; C.A. Forster, and C.L. May. 2001. Paleoenvironment and taphonomy of the Chañares Formation tetrapod assemblage (Middle Triassic), northwestern Argentina: spectacular preservation in volcanogenic concretions. Palaios 16. 461–481.

Sereno, P. C., A. B. Arcucci. 1994. "Dinosaurian precursors from the Middle Triassic of Argentina: Marasuchus lilloensis, gen. nov". Journal of Vertebrate Paleontology. 14 (1): 53–73.

[rmyers08]

When I was a kid Saltopus was still a dinosaur. There was a song and everything ... #drawdinovember #dinovember #dinosauromorph #saltopus #triassic #paleoart #pencil #doodle #artistsoninstagram https://www.instagram.com/p/Bp8VfsqlxTA/?utm_source=ig_tumblr_share&igshid=1tjk3fio11vtu

[a-dinosaur-a-day]

Nyasasaurus parringtoni

By José Carlos Cortés on @quetzalcuetzpalin-art​

PLEASE SUPPORT US ON PATREON. EACH and EVERY DONATION helps to keep this blog running! Any amount, even ONE DOLLAR is APPRECIATED! IF YOU ENJOY THIS CONTENT, please CONSIDER DONATING!

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. 

Shout out goes to @thea-wood!

[a-dinosaur-a-day]

Technosaurus smalli

By Jack Wood on @thewoodparable

PLEASE SUPPORT US ON PATREON. EACH and EVERY DONATION helps to keep this blog running! Any amount, even ONE DOLLAR is APPRECIATED! IF YOU ENJOY THIS CONTENT, please CONSIDER DONATING!

Name: Technosaurus smalli

Name Meaning: Tech Reptile

First Described: 1984

Described By: Chatterjee

Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Silesauridae

Technosaurus is probably a Silesaurid, but it was named by Chatterjee, who isn’t exactly the most robust or thorough scientists out there when it comes to describing early Dinosauromorphs. In fact, the original fossil was determined to be a chimera - which is fairly typical for Chatterjee - with only a part of the jaw being thought to be that of a Silesaurid, though that’s under debate, and it can’t be confidently be said to be anything more than an Archosauriform. It lived in the Bull Canyon Formation of Texas, in the Norian age of the Late Triassic, about 210 million years ago. 

Source:

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

Shout out goes to @2coolworld!

[a-dinosaur-a-day]

Silesaurus opolensis

By José Carlos Cortés on @quetzalcuetzpalin-art​

PLEASE SUPPORT US ON PATREON. EACH and EVERY DONATION helps to keep this blog running! Any amount, even ONE DOLLAR is APPRECIATED! IF YOU ENJOY THIS CONTENT, please CONSIDER DONATING!

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

Shout out goes to @hammuffins!