To kick off the back to school season, this week's post is a random assemblage of temnospondyl superlatives, some more informative than others!
The smallest temnospondyl (?) This one is much harder to figure out. For one, you have to separate small, immature specimens from small, mature specimens, which if you keep up to date on my metoposaurid projects, you know is a big sticking point for me. In a lot of instances, the evidence isn't as unequivocal as we'd like - you can't histologically section just any skull, for example, to get a more precise age of a specimen. You also have to make a bunch of assumptions about how a given taxon developed. For example, did it hit skeletal maturity and then still continue to increase in size by a discernible amount, or did it reach its maximum size when it reached maturity? Without growth series, which are lacking for many extinct animals in general, it's hard to know one way or the other. Therefore, I'll just toss out a few that are definitely among the contenders for this category. On the Paleozoic side of things, the group with the most candidates would be the dissorophoids. Many branchiosaurids have skulls less than 2 cm long, as do a number of the non-branchiosaurid amphibamiforms and some micromelerpetids. Some of the earliest dvinosaurs, such as Eugyrinus wildi, are in the same ballpark, but they're a little trickier in terms of the interpretation of their maturity. Most of the Mesozoic temnospondyls are gigantic, but there are a few small groups out there. Lapillopsids, an Early Triassic group from the southern hemisphere are one of those groups. A second group is the rileymillerids (sometimes the latiscopids), like Rileymillerus and Chinlestegophis from the Late Triassic of North America. Best-known temnospondyl (generally speaking) This will no doubt inspire some controversy because there is no T. rex equivalent for temnospondyls. In many cases, the "best-known" one is the one that amniote workers encounter while looking for amniote fossils. In North America, probably the top three candidates would be Eryops, the classic large-bodied early Permian taxon, Dendrerpeton (but in most cases actually Dendrysekos), which gets used all the time for an outgroup in phylogenetic analyses, and metoposaurids, not because I'm the one writing this blog but because they're so ubiquitous in the Late Triassic, which is well-exposed across huge swaths of North America and obviously a major hotspot for paleontologists looking for early dinosaurs (also literal millions of people have seen the one at the AMNH). Never having lived on another continent, I am less qualified to make any claims regarding popular temnospondyls in other areas, but Europe has some of the best temnospondyl displays in museums, like Mastodonsaurus and Sclerocephalus. Metoposaurids (including the OG Metoposaurus) and the long-snouted trematosaurs are quite ubiquitous over there too. Africa has a real hodgepodge of temnospondyls, but Lydekkerina is a classic taxon described over 150 years ago that's well-known from the Early Triassic of South Africa. Temnospondyls remain relatively undersampled in South America, Asia, and Antarctica, so there isn't a particularly diverse pool to choose from in those areas. Australia has Koolasuchus, which even though it's very fragmentary, made it onto an Australian postage stamp and a BBC documentary, so you could argue that it's the most famous globally, even if not too many people know it by name. Most commonly confused name This honour goes to a few taxa that have names very similar to more charismatic taxa such that Google always pulls up the infamous "Do you mean..."
Weirdest temnospondyl If you ask me, this one isn't really that controversial - it has to be Zatrachys and co. in the family Zatracheidae. Not only do these temnos have particularly spiky heads, but they also have this gigantic hole in their snout called the internarial fontanelle (the thing coloured in violet on the bottom left). Other temnospondyls have internarial fontanelles but not nearly to this degree. Zatrachys is from North America, but its cousin from England, Dasyceps, is arguably just as weird and has an even more peculiar skull shape.
Best cuddler This is also not really a contest. In 2013, the most complete specimen of the rhinesuchid Broomistega from South Africa was reported in a burrow (Fernandez et al., 2013). However, Broomistega is fully aquatic and is not thought to be a burrowing animal. In fact, the burrow that it was found in also contains a complete skeleton of the synapsid Thrinaxodon, who probably did make the burrow. Both animals are completely articulated and show no evidence of having died mid-fight (a la the famous Velociraptor-Protoceratops fossil fight). The temnospondyl has had a bit of a rough time - it has numerous healed ribs and two puncture holes in the top of its head (that don't match with the teeth of Thrinaxodon). Cohabitation in a single burrow is not very common among vertebrates, so it is suggested that the temnospondyl was either tolerated by the synapsid, or, as the authors put it, the synapsid "was not able to evict it" (probably due to the synapsid being in a state of aestivation i.e. not really being conscious). As such, the temno probably crawled into the burrow to seek some refuge, perhaps from drought, and then both of these animals ended up getting killed by a flood that inundated their cozy burrow. Refs
David Marjanović
9/6/2019 12:20:58 pm
"Balanerepton is within the temnospondyl family Dendrerpetidae" Comments are closed.
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