Sunday, November 10, 2019

Ferrisaurus sustutensis

You may have come across a reference to the Sustut dinosaur over the years. It's now been formally described as a new genus and species of leptoceratopsid dinosaur: Ferrisaurus sustutensis. Victoria Arbour, as lead author and someone who has dealt with this specimen for nigh-on fifteen years, has a personal take over at Pseudoplocephalus. For those of you playing along at home, Ferrisaurus is the first named nonavian dinosaur from British Columbia.

Genus and species: Ferrisaurus sustutensis. This one's fairly self-explanatory: the genus name means "iron lizard" ("ferrum" as the basis of the first part of the name), referring to the discovery locality being near a railroad, and the species name refers to the Sustut River and Sustut Basin, producing something like "iron lizard of Sustut" (Arbour and Evans 2019).
Citation: Arbour, V. M., and D. C. Evans. 2019. A new leptoceratopsid dinosaur from Maastrichtian-aged deposits of the Sustut Basin, northern British Columbia, Canada. PeerJ 7:e7926. doi:10.7717/peerj.7926.
Stratigraphy and geography: The type and only known specimen came from rubble attributed to the Tatlatui Member of the Tango Creek Formation, featuring late Maastrichtian palynomorphs (nonmineralized organic microfossils: pollen, spores, and so forth). The site was along the now-abandoned BC Rail Line, near the confluence of Birdflat Creek and Sustut River in the Sustut Basin, north-central British Columbia, Canada (Arbour and Evans 2019).
Holotype: Royal British Columbia Museum (RBCM; Victoria, British Columbia) P900, previously RBCM.EH2006.019.0001 to RBCM.EH2006.019.010. RBCM P900 consists of a "partial right coracoid, fragmentary left scapula, complete left radius, distal portion of the left ulna, associated distal two thirds of the left tibia and fibula and coosified astragalus and ?calcaneum, partial articulated digits III and IV of the right pes, and an unprepared block removed from the posterior surface of the tibia that appears to contain four metatarsals, presumably from the left pes" (Arbour and Evans 2019).

Put that list all together, and here's what you've got; Figure 2 from Arbour and Evans (2019). CC-BY-4.0.

RCBM P900 is one of those specimens that has been out there for a while. The bones were collected in 1971 by Kenny F. Larsen, a geologist looking for uranium along the then-under-construction rail line. Additional work in the area allowed the authors to determine that the source was probably the Tango Creek Formation, not the Brothers Peak Formation as reported in Arbour and Graves (2008). The type specimen is not the easiest to interpret, and previously had been tentatively reported as a pachycephalosaur or Thescelosaurus-type hypsil (Arbour and Graves 2008) before arriving at its current home. A leptoceratopsid identity is more consistent with the blocky, stocky phalanges, as well as the relatively long and robust arm. At the same time, the phalanges are also inconsistent with a juvenile ceratopsid or hadrosaur. As a leptoceratopsid, RCBM P900 would have been a large individual, with some indications that its arms were proportionally short for that group, but also robust. This could indicate that it was more bipedal than some other leptoceratopids, or that it was doing something with its arms that favored short strong proportions, such as digging (Arbour and Evans 2019).

It wasn't something that was hit on in the publication, but the locality would have been on the west side of the growing North American Cordillera, separated from the classic localities to the east in Alberta, Montana, Wyoming, and the Dakotas. Currently, we don't know much about what was living on the west side of the mountains in the Cretaceous. I'd be interested in knowing if the mountains would have been a barrier to movement, but that's not a question we can answer at this time.

Leptoceratopsidae is made up of about a dozen species as of press time, mostly from the Campanian–Maastrichtian of North America, but with a few from Asia or earlier in the Late Cretaceous, the biggest outlier being Asiaceratops salsopaludalis from the Cenomanian of Uzbekistan. As ceratopsians but not true ceratopsids, they had short frills, but no brow or nasal horns (in case you missed it, the "nasal horn" of Montanoceratops is a jugal horn). Leptoceratopsids were one of three basic varieties of smallish ornithischians known to have lived in western North America during the Late Cretaceous, the others being the pachycephalosaurs and thescelosaurs/parksosaurs. Like many members of those other two groups, leptoceratopids were fairly chunky; in fact, considering Leptoceratops, Pachycephalosaurus, and Thescelosaurus, one gets the impression that end-Cretaceous small ornithischians of western North America were through running.

Haven't had one of these for a while. Click to embiggen the Leptoceratopsidae.

Even though leptoceratopids were so-called basal ceratopsians living at the end of the Cretaceous, it's not as though they were some kind of remnant of early ceratopsians that failed to evolve into ceratopsids. They were a distinct lineage filling distinct ecological spaces and getting along quite well at it. Anatomically, they're kind of weird; I'll pause here to let you get out your preferred quick anatomical reference. Anyway, leptoceratopsids had big heads with deep jaws, proportionally short and narrow hips, and short tails (restorations vary as to just how much, but these aspects are certainly true in the general). There's something piggish about them, actually: pigs equipped with gardening loppers. Herbivores, omnivores, whatever, you certainly wouldn't want to put your hand in front of them.


Arbour, V. M., and D. C. Evans. 2019. A new leptoceratopsid dinosaur from Maastrichtian-aged deposits of the Sustut Basin, northern British Columbia, Canada. PeerJ 7:e7926. doi:10.7717/peerj.7926.

Arbour, V. M., and M. C. Graves. 2008. An ornithischian dinosaur from the Sustut Basin, north-central British Columbia, Canada. Canadian Journal of Earth Sciences 45(4):457–463.

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