A Week in Croc News: A ziphodont crocodilian from New Guinea and a "baby" Piscogavialis
Once again I'm here to recap exciting fossil croc news. To give a quick rundown of papers from the last week, we had one on non-semi aquatic adaptations in crocodylomorphs (mostly life on land but also notes of marine groups), a paper that I'm biased toward because it feaures two of my silhouettes in its phylogeny.
The two silhouettes of mine used in the study. Duerosuchus representing the Planocraniidae and Trilophosuchus representing Atoposaurids (eventhough it's not one, it was picked since it at least conveys the right proportions).
Thalattosuchians recieved a lot of attention this past week. For starters, in addition to being brought up in the afforementioned paper, they were given a lot more focus in a study comparing the function and phylogenetic importance of their shoulder girdles (and those of dyrosaurids), a metriorhynchoid skeleton of uncertain affinities from the Cretaceous northeast Italy was described and just today we got a study on the braincase anatomy of Thalattosuchus.
The one paper that excited me the most however was the description of ziphodont crocodilian teeth from the Pliocene Otibanda Formation of Papua New Guinea. To those unaware, ziphodont teeth are essentially teeth that are flattened like a blade and bear serrations along their cutting edge, something seen in dinosaurs, monitor lizards and a select few crocodile groups like sebecid notosuchians, planocraniids and some mekosuchines. Now these teeth are nothing new, they've been known since 1967, hell I even mentioned them on both the wikipedia pages for Mekosuchinae and Quinkana, but they were never properly described...until now.
Leave it to Jorgo Ristevski, Ralph Molnar and Adam Yates to tackle this one, describing not just the ziphodont teeth but also the postcranial material and conical teeth from the formation. Now don't expect any new species or genera. Though valuable, the study doesn't cause any major stirr ups. The ziphodont teeth are tentatively referred to the Mekosuchinae, though they are not morphologically distinguishable from other ziphodont groups like sebecids or the previously mentioned planocraniids, mekosuchines are the only ones that fit the time and location. The other fossils are even more ambiguous, the postcrania referred to Crocodylia incerta sedis and the conical teeth to cf. Crocodylus sp., so basically an unknown crocodilian and a modern croc. This at least suggests that two different crocodiles inhabited Papua New Guinea at the time, maybe even three assuming that the postcrania don't belong to either the ziphodont or conical form.
Since New Guinea and Australia were once connected, forming the continent of Sahul, some Quinkana-like mekosuchines could have easily traveled to the island.
The final thing I want to mention is not an actual study, but still newsworthy. Scientists in Peru just revealed whats thought to be the first juvenile Piscogavialis. An amazingly preserved skeleton was unveiled, preserving much of the skull minus the tip of the snout, most of the spinal collumn until the base of the tail, both hindlimbs and some other bones as well (from the photos theres a few ribs at least).
Whats fun is that though described as a juvenile, the animal is estimated to have already reached around 3 meters in length. To put this into perspective, thats the size of the average female saltwater crocodile and just shy of the 4.3 meters reached by the contemporary Sacacosuchus. Now on the one hand, I think calling that a juvenile might be a bit of an exaggeration (then again the term subadult is arguably vague and meaningless) and I'm curious to see whether or not an eventual study will back this up with anatomical features or if its even possible that it could just be an instance of dimorphism between sexes. But thats just me musing on the basis of a few photos.
Anyways, given that they just state that this 3 meter animal is a "juvenile", you might wonder how large the adult would be?
The short answer...large.
Yeah Piscogavialis got big. The skull alone measures over a meter in length and a recent paper on Sacacosuchus said that they grow to nearly twice the length of their smaller contemporary. With Sacaco sitting at 4.3 meters, one could easily imagine Piscogavialis reaching 7 to maybe 8 meters (I should make a proper scaling at some point). Here's how Gabriel Ugueto and artbyjrc scaled this animal and yeah, even if it ate fish it could probably do some real damage if provoked.
