here's this week's #Paleostream flocking sketches (im late because i was swamped with uni work)

this week we sketched Sharovipteryx, Sinopterus, Pachycrocuta, and Ptolemaia

During the mid-Cretaceous Brazil was a hotspot of pterosaur diversity. This local abundance of potential prey drove one predator to fill the niche. A spinosaur related to Irritator and Angaturama began to specialize in hunting pterosaurs rather than fishing. This behavior was only opportunistic at first, but within a few million years notable adaptations have emerged. The animal is smaller and lighter than it's ancestors and its hindlimbs are proportionally longer and more cursorially adapted. These allow it to explosively chase and leap at pterosaurs while they are still attempting to launch. The neck and jaws are longer to reach further up during a leap, letting it catch pterosaurs even further off the ground. The arms are proportionally shorter, as they were less useful for prey capture than the jaws. The shoulders are more mobile than their ancestors', allowing the arms more range of motion to balance during a leap. The preferred prey of this specialized spinosaur are Tapejarids and Anhanguerids. The former because they are terrestrially competent and initially run to escape, only reluctantly resorting to flight to escape. The latter because their proportions, while great at crossing the sea, make them awkward and slower to takeoff from a grounded position. During lean seasons these adaptations are also useful at capturing small terrestrial game when pterosaurs are migrating or otherwise absent

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Pterosaur Sinopterus dongi, of Early Cretaceous, China!

Our next archosauromorph, and our first pterosaur of Archovember is Sinopterus dongi. Sinopterus dongi is a small tapejarid from Early Cretaceous, China, known for being one of the first pterosaurs with direct evidence pointing to it being a herbivore, or at most an omnivore, based on the remains of plant matter and gizzard stones found in its gut. Like other tapejarids, Sinopterus had a large Toucan-like skull filled with air pockets that would have made it lightweight. It is known from several specimens at various stages of growth, which has allowed scientists to study the changes these animals went through during their lifespan. Based on wing proportions and bone strength/flexibility, Sinopterus flaplings seemed to be capable of powered flight very shortly after hatching. Juveniles also seem to have been more adapted to flight in closed environments, like dense forests, compared to adults. Juveniles therefore probably occupied different ecological niches than adults, transitioning between different niches as they grew.

Sinopterus dongi lived in the Early Cretaceous Jiufotang Formation of Chaoyang, Liaoning, China. It shared this forested environment with the famous dromaeosaur Microraptor, as well as other slightly less famous theropods like Sinotyrannus, Jeholornis, Wulong, Similicaudipteryx, Sapeornis, Omnivoropteryx, Neimengornis, Kompsornis, Cratonavis, Confuciusornis, Chongmingia, Zhongjianornis, Yixianornis, Yanornis, Songlingornis, Shuilingornis, Similiyanornis, Imparavis, Musivavis, and more. While the forest may have seemed dominated by birds, there were still plenty of other pterosaurs as well, including Chaoyangopterus, Eoazhdarcho, Forfexopterus, Guidraco, Hongshanopterus, Huaxiadraco, Ikrandraco, Liaoningopterus, Liaoxipterus, Linlongopterus, Meilifeilong, Nemicolopterus, Nurhachius, Pangupterus, and Shenzhoupterus. The forest environment of the Jiufotang was mainly suited for the small, feathery, and the fluffy, but a few larger Ornithischians lived here as well, including the ankylosaurs Chuanqilong and Liaoningosaurus, and the Psittacosaurus’ P. meileyingensis and P. mongoliensis, and evidence of at least one large titanosaur is present in the formation.

this was an art trade with fishfriend (who I don’t think has a tumblr)

he’s a great potter but I traded for a bunch of his patches. his cave art style horses and goat patches were just too tempting to pass up.

here’s what he sent me (also a couple stickers which are already on my desk!)

and he takes commissions for pottery, stamps, patches and shirts! here’s an example of one of his ceramic pieces

and some of his shirts

I Pseudosauropod paraxenos, mid triassic - Native to an unnamed island off the south-western coast of Pangea, Pseudosauropod might be the first large dinosaur in history. Descended from small insectivores that dispersed there through drifting it inhabits an island never reached by pseudosuchians or synapsids, which allowed those small creatures to quickly fill the megafaunal niche and become large herbivores. Despite it's close resemblance to sauropodomorphs it is actually a basal theropod hovewer at this point in time it hasn't been long since those two groups split. Ultimately an evolutionary dead end, it is nevertheless a forecast of things to come.

II Melisodon nakamuri, late jurassic - While almost all non-mammalian synapsids vanished at the end of triassic, few non-mammal cynodonts managed to make it through into the jurassic. Among them was a lineage of the very last cynognathids, still clinging on in Antarctica. As time passed, some of them found themselves on an isolated island chain off the southernmost continent. On the islands they flourished and diversified into many different niches, thriving long after the extinction of their brethren on the mainland. They survived up until the jurassic-cretaceous boundary, when environmental changes ultimately led to their demise, making them the last non-Probainognathian synapsids to have ever lived. Melisodon, a relatively large omnivore of the end jurassic is one of the last species in the lineage.

III Adamatherium kynodontis, mid cretaceous - Animal hailing from a sizeable island in eastern Tethis Ocean. This land has no non-avian dinosaurs, however it was reached by several mammals from few different clades, that dispersed there by drifting. With the limitations posed by archosaurs largely gone, small furry creatures quickly evolved to fill almost all available niches on the island. From weird specialised omnivores, through megafaunal grazers to apex predators. This small kingdom became a "cenozoic before cenozoic", showing how quickly animals can evolve and flourish if given a chance. Adamatherium is a herbivorous multituberculate, and the largest animal on the island. Reaching the size of a cow, it is the largest mammal to have yet existed, and it will only be matched after several tens of millions of years.

IV Balearosaurus parvus, late cretaceous - This small iguanodont is a fascinating case of convergent evolution to Balearic Island cave "goat" (a real, bizarre animal killed off by humans just few millenia ago). It's story began when their small island separated from the landmass of future Spain, isolating few animals there from the outside world. Balearosaur's ancestors found themselves in a very small place, with no predators and almost no competition, but extremely limited resources, which demanded extreme adaptations. Over time their legs became shorter and weaker, with the animal losing it's ability to run, as it would be an unneeded waste of energy in this predator free environment. Lack of predator also caused another adaptation - forward facing eyes, an unnerving sight in a herbivore. Due to very limited access to calories they became much smaller from their ancestors, and developed an extreme adaptation - ectothermy. With slower metabolism and body heat controlled by external temperatures the animal can conserve more energy, making it perhaps the only cold blooded dinosaur in history. Yet eventually the island moved closer to larger landmasses again, meaning it became available for frequent visits by large azhdharids. With a sudden reappearance of predators Balearosaurus vanished in just a few generations.

V Contritodactylus maxima, late cretaceous - It is much rarer for flightlesness to evolve in pterosaurs that it is in birds, but with the right conditions it can still happen. Contritodactylus is a giant flightless tapejarid, native to a large but really isolated island in the Pacific. It's ancestors were lightweight frugivores, caught in a tropical storm and carried off course into the fated land. Here they found themselves in a place with an abundance of food but basically no land predators big enough to pose a serious threat, maybe with an exception of some large lizards. The island was also the only food source within a flying range. Those conditions caused many descending species to lose their ability to fly, and fill land dwelling niches. Contritodactylus is a specialised browser, with it's massive beak used to strip branches of fresh leaves, pick and crush fruit and crack open nuts and seed pods. It is also the heaviest pterosaur on the planet at that particular time period.