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Teleocrater rhadinus

By Ripley Cook

Etymology: Completed Basin

First Described By: Nesbitt et al., 2017

Classification: Biota, Archaea, Proteoarchaeota, Asgardarchaeota, Eukaryota, Neokaryota, Scotokaryota Opimoda, Podiata, Amorphea, Obazoa, Opisthokonta, Holozoa, Filozoa, Choanozoa, Animalia, Eumetazoa, Parahoxozoa, Bilateria, Nephrozoa, Deuterostomia, Chordata, Olfactores, Vertebrata, Craniata, Gnathostomata, Eugnathostomata, Osteichthyes, Sarcopterygii, Rhipidistia, Tetrapodomorpha, Eotetrapodiformes, Elpistostegalia, Stegocephalia, Tetrapoda, Reptiliomorpha, Amniota, Sauropsida, Eureptilia, Romeriida, Diapsida, Neodiapsida, Sauria, Archosauromorpha, Crocopoda, Archosauriformes, Eucrocopoda, Crurotarsi, Archosauria, Avemetarsalia, Aphanosauria

Status: Extinct

Time and Place: Possibly 247 million years ago, in the Anisian age of the Middle Triassic

Teleocrater is known from the Lifua Member of the Manda Formation in Tanzania

Physical Description: Teleocrater was a long, slender reptile measuring 2.1 to 3 meters long from snout to tail tip. It had a long, narrowing skull with small, very pointed teeth lining the insides. Its nostrils were at the tip of its snout, while its eyes were deep in its head. In a lot of weird ways, its skull kind of looked like that of a Monitor Lizard. However, it was no lizard. It had a very long neck, with some of the longest neck vertebrae of any bird-line Archosaur (Avemetatarsalia). These vertebrae were weirdly ornamented in addition to long, which turns out to have been a defining feature of this early offshoot in the bird-line group (Aphanosaurs). These vertebrae get taller and taller as they continue down the neck, unique for Teleocrater. It only had two vertebrae on its pelvis, unlike the contemporaneous dinosaur Nyasasaurus that had three, indicating its lower position on the bird-line tree. It also had small nubbins coming off of its ribs like seen in other early Avemetatarsalians. It had long legs, going out to the sides and not under the body, with very small hands and normally-proportioned feet. It didn’t have very long feet compared to its legs like those seen in Ornithodirans, indicating it wasn’t very fast or adapted to running like in those other animals. Despite being in Avemetatarsalia, Teleocrater had an ankle more closely like those of the ancestral condition - ie, the crocodilian ankles rather than the firmly connected ankles of the pterosaurs and dinosaurs. Teleocrater also had a long tail, giving it an overall very elongated appearance.

It is uncertain what Teleocrater would have been covered in. It is a very distinct and notable mid-point in the bird-line evolution - it is a part of the earliest group to branch off on this portion of the tree of life and it lacks many of the defining characteristics of Avemetatarsalians, including the one from which they got their name. That said, it doesn’t preserve osteoderms like in Pseudosuchians, indicating that these structures were lost in even the earliest Avemetatarsalians (and only regained later in some unique dinosaur groups). So - did it have floof? We don’t know. We probably will never know. Unlike other small bird-line archosaurs of the time, it’s a 50/50 shot.

Diet: Thanks to the very well preserved teeth, we know for a fact that Teleocrater was a carnivore.

Behavior: Teleocrater may have oddly resembled living monitor lizards from a far and may have had much in common with living Crocodilians in its skeleton, but it - like other early Archosaurs - would have most likely been endothermic, living a very active lifestyle. The bones of this animal indicate that it grew rapidly, much more so than earlier archosaurs (which have decent evidence for at least partial endothermy), though less so of dinosaurs and pterosaurs. This would have looked interesting with its splayed-out legs, and it probably would have run very clumsily and slowly given its small hands and non-adapted for fast movement feet. That said, it could have used its increased activity to aid in catching prey that other reptiles couldn't, to help get away from predators, and in general be a weird active possibly fluffy lizard dude. You know. Like Varactyl from Star Wars Episode III: Revenge of the Sith. Except without front feet. Or, useful front feet. It was weird. It may or may not have been social. We have no evidence either way - while it was common, it was also a carnivore, so it probably wouldn’t have gotten much out of being in social groups in such a crowded ecosystem. That said, it was an archosaur, and archosaurs should be assumed to take care of their young without evidence to the contrary. Modern archosaurs across the board, except the weird and highly unique Megapodes, take care of their young - so Teleocrater would have too. That said, both Crocodilians and Birds have unique nesting strategies, so we can’t look to them for clues into how Teleocrater took care of its young.

Ecosystem: Teleocrater lived in the amazing Manda Beds Formation, a seasonally arid river valley floodplain in the heart of Tanzania where many early and fascinating reptiles appeared as the Triassic began to go into full swing. Teleocrater probably came at least a little earlier than more famous animals of the formation - it comes from the Lower portion of the Lifua Member, while Asilisaurus and Nyasasaurus, among others, came from the Upper portion. That said, it wasn’t much earlier, and the exact ecology is still a little murky. Teleocrater itself was found with the large Dicynodont Dolichuranus, the smaller cynodont Cynognathus, the temnospondyl Stanocephalosaurus, an unnamed Allokotosaurian, and the Ctenosauriscid Hypselorhachis. So, the explosion of the reptiles was still not quite there - but Teleocrater represented change in the winds to come. It probably would have been able to feed on many of the other animals in its environment, given its fairly large size.

Other: Once upon a time, a fossil that would tell us much about the evolution of bird-line archosaurs and ruling reptiles in general sat unstudied in a cabinet in the Natural History Museum of London. Then, a young scientist described this animal as Teleocrater in a PhD Thesis - which means it wasn’t officially named, making it a nomen nudum - a naked name. It would take nearly sixty years for more parts of Teleocrater - parts that could actually be described and talked about, as opposed to the locked-away remains of the thesis - to be found and properly described, bringing us Teleocrater, officially, at last. This important discovery was of the oldest bird-line Archosaur known, beating the previous record holders, Asilisaurus and Nyasasaurus, by quite a few million years. It helped to piece together the evolution of the bird-line Archosaurs, see where certain traits (including the famed ankles) actually appeared, and also lead to the formation of a new group of animals entirely - the Aphanosaurs. Many weird early dinosaur-esque creatures that formerly didn’t have a home have now been placed in the Aphanosaur group, giving them a home at last - and showing how diverse bird-line archosaurs were outside of the famed Dinosaurs and Pterosaurs. Given their fast growth rate and potential fluff (though that’s a 50/50 shot) but splayed out legs and lizard-like appearance they - rather than dinosaurs - probably deserve the name “Lizard-Birds”, as they look like lizards, but their closest living relatives are birds. Other Aphanosaurs include Yarasuchus, Spondylosoma, and Dongusuchus.

~ By Meig Dickson

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