monotypic, including only the species Jupijkam paleofluvialis. It is based on a partial skull and a few other fragments (including an osteoderm) from the White Water Member of the Blomidon Formation. Along with unnamed fossils from the Fleming Fjord Formation of Greenland, these remains represent the northernmost record of phytosaurs. Jupijkam is named after Jipijka'm, the great horned serpent of Mi'kmaq mythology.[1]
Fossils of Jupijkam were previously referred to
mystriosuchine). Most Rutiodon-grade phytosaurs were extinct prior to the late Norian, but Jupijkam survived up to the latest Norian or early Rhaetian.[1]
History and naming
Jupijkam is known from a singular, only partially preserved skull as well as a complete osteoderm and various bone fragments, all of which had been discovered in 1974. The fossils of the genus stem from the White Water Member of the
Yale Peabody Museum
. The fossil material wasn't described until 2023, when C. D. Brownstein named the genus and species.
The genus name Jupijkam is derived from the
Mi’kmaq
mythology, which is also known as Jipijka’m, Chepechcalm and Tcipitckaam. The name was chosen as the Mi'kmaq are the original inhabitants of Nova Scotia. The species name derives from Latin words "palaeo" and "fluvialis", meaning "ancient" and "river" respectively, chosen to reflect the animal's likely habitat.
Description
Jupijkam was a large-bodied phytosaur with an extremely elongated (longirostrine) and gracile snout. Brownstein compares the proportions of this animal to phytosaurs like
Machaeroprosopus lottorum among others, contrasting with the much more robust morphology seen in Pravusuchus, Colossosuchus
and other species of Machaeroprosopus. Like in other phytosaurs, the rostrum rises abruptly towards the back of the skull, elevating the nostrils high above the jawline just before the eyes. However, little can be said about the precise anatomy of Jupijkam beyond the jaws, as the back of the skull is not preserved.
The jaws end in a rosette of teeth formed by the
premaxillae, with four teeth present in either side. This rosette is only moderately downturned, which makes it similar to most other phytosaurs and differentiates it from Machaeroprosopus and Colossosuchus. The fourth tooth, like in other parasuchids, is noticeably smaller than the first three and separated by all other subsequent premaxillary teeth by a short, toothless gap (diastema). Behind this diastema, each premaxilla bears 19 additional teeth, each of which is more widely spaced from the others than typical for longirostrine phytosaurs. On the side of the premaxillae, about 5 mm (0.20 in) above the toothrow, lies a deep groove that contains the neurovascular foramina. This groove is much deeper than in other taxa and runs along nearly the entire length of the rostrum, only ending just behind the beginning of the antorbital fenestra
.
The rostrum as a whole lacks extensive ornamentation or ridges except for the occasional foramina. This lack of ornamentation also extends to the septomaxillae, which aren't strongly arched either. A pair of thick bones located before and towards the sides of the
nares which seem to match the paranasals seen in several species of Machaeroprosopus. Such bones are not known from all phytosaurs and their relationship to the skull bones of other archosaurs remains unclear. Unlike in Machaeroprosopus, the potential paranasals of Jupijkam are directed much more towards the side of the skull rather than upwards. The nasal bones
are not inflated.
Phylogeny
Given the contentious state of phytosaur
parsimony analysis
found Jupijkam as a mystriosuchine outside of Leptosuchomorpha.
Bayesian analysis meanwhile found very different results for both datasets. Utilizing Bayesian tip-dating analysis of the Jones and Butler dataset, Jupijkam was recovered as a sister taxon to Mystriosuchus
, whereas Bayesian tip-dating analysis of the Datta and Ray dataset was more in line with the previous parsimony analysis, finding it to group with Rutiodon, except now to the exclusion of Volcanosuchus.
While all these analysis produce different results, it has been noted that in no analysis does it clade with the other known Late Triassic phytosaurs. This would suggest that Jupijkam represents a lineage that independently survived until the Norian-Rhaetian boundary.