So, in the midst of the thousand thousand other projects I have started, on this website and in life…I just wanna have some fun with art. Not the best artist, so forgive my trespasses here, especially with a dinosaur species I’ve, admittedly, never heard of! Neat one, though! This is a part of the #DrawDinosDaily challenge posted by @a-dinosaur-a-day, so I’ll try and do as many of these as I can this month (or…year?)!
So, middle Triassic dinosaur known from fossils in Tanzania, which is super neat! He’s kind of a weirdy, with longer front limbs, functional fifth toes, a toothless front of the mouth, and an unclear phylogenetic relationship to a primitive group of the dinosaurs, the silesaurids. I skimmed a few papers (unaccustomed to reading paleontological species description papers, so that was a lot of jargon), got some vibe of the guy, and put him to paper! Or iPad.
The potential inaccuracies in my depiction are the implications of feathers (no direct evidence, especially for a dinosaur this old, but there is some academic speculation that feathers may be this early), the way the feet are drawn (that was a lot harder than I thought it would be, but I think I got that functional fifth toe right in there), and the length of the front limbs (they ARE long, but I leant into some older interpretations of the species). So, to my fellow dinosaur lovers, sorry about that! Been a while since I’ve drawn a non-avian dinosaur, and certainly not in this style. Hopefully, sticking with this challenge helps me improve a bit! Next up, the Bearded Reedling (Panurus biarnicus)!
Anya is live and ready to show you everything. Watch her strip, dance, and perform exclusive shows just for you. Interact in real-time and make your fantasies come true.
✓ Live Streaming✓ Interactive Chat✓ Private Shows✓ HD Quality✓ Free Actions
Free to watch • No registration required • HD streaming
Spec-Dinovember Day 3: Fan Favorite, a member of an obscure group filling the niche of a much more popular dinosaur
During the Late Triassic the large herbivore niches were occupied by 'prosauropods,' early sauropods, and the last giant dicynodonts. But, in a far-flung corner of Pangea where no member of these groups managed to reach, a different archosaur has become the resident high-browser. Silesaurids are an unassuming group of either near-dinosaurs, or stem-ornithischians depending on who's phylogeny you look at. In the absence of larger herbivores these little insectivorous sprinters had the opportunity to slow-down and grow huge. Maxing out at a few tons these are not small animals anymore, but they pale in comparison to the Jurassic sauropods that will eventually outcompete them.
This prompt was kind of tough, I had to wrack my brain to think of an obscure dinosaur group that could plausibly be squished into the shape of one of the really famous ones. I finally settled on this idea because A) Silesaurids feel pretty obscure, and not everyone who knows about them even consider them dinosaurs, and B) I could call it a "Silesauropod!"
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.
Anya is live and ready to show you everything. Watch her strip, dance, and perform exclusive shows just for you. Interact in real-time and make your fantasies come true.
✓ Live Streaming✓ Interactive Chat✓ Private Shows✓ HD Quality✓ Free Actions
Free to watch • No registration required • HD streaming
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!
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.
