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| Ferrisaurus sustutensis
Arbour & Evans, 2019
DOI: 10.7717/peerj.7926
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Abstract
A partial dinosaur skeleton from the Sustut Basin of northern British Columbia, Canada, previously described as an indeterminate neornithischian, is here reinterpreted as a leptoceratopsid ceratopsian, Ferrisaurus sustutensis, gen. et. sp. nov. The skeleton includes parts of the pectoral girdles, left forelimb, left hindlimb, and right pes. It can be distinguished from other named leptoceratopsids based on the proportions of the ulna and pedal phalanges. This is the first unique dinosaur species reported from British Columbia, and can be placed within a reasonably resolved phylogenetic context, with Ferrisaurus recovered as more closely related to Leptoceratops than Montanoceratops. At 68.2–67.2 Ma in age, Ferrisaurus falls between, and slightly overlaps with, both Montanoceratops and Leptoceratops, and represents a western range extension for Laramidian leptoceratopsids.
Systematic palaeontology
DINOSAURIA Owen, 1842
ORNITHISCHIA Seeley, 1888
NEORNITHSICHIA Cooper, 1985
MARGINOCEPHALIA Sereno, 1986
CERATOPSIA Marsh, 1890
NEOCERATOPSIA Sereno, 1986
CORONOSAURIA Sereno, 1986
LEPTOCERATOPSIDAE Nopcsa, 1923
FERRISAURUS SUSTUTENSIS gen. et sp. nov.
Diagnosis: Ferrisaurus can be differentiated from other known leptoceratopsids based on the following unique combination of characters: penultimate pedal phalanges in digits III and IV are equal or subequal in proximodistal length compared to the length of the preceding phalanx, rather than shorter as in all other leptoceratopsids for which these elements are preserved except possibly USNM 13863 (Cerasinops); astragalus and tibia coossified, unlike all other leptoceratopsids except for AMNH 5464 (Montanoceratops); distal end of ulna broader relative to radius length than in Leptoceratops; distal end of ulna medially bowed, unlike the straight ulna of the penecontemporaneous Maastrichtian taxa Leptoceratops and Montanoceratops, but similar to Cerasinops and Prenoceratops from the Campanian.
Etymology: “Iron lizard,” from Latin ferrum (=iron) and Greek sauros (=lizard), in reference to the specimen’s discovery along a railway line, and sustutensis in reference to its provenance near the Sustut River and within the Sustut Basin.
Holotype: RBCM P900, a partial skeleton consisting 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 coossified astraglus 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. Previously catalogued as RBCM.EH2006.019.0001 to RBCM.EH2006.019.010 and published under RBCM.EH2006.019 by Arbour & Graves (2008).
Locality: RBCM P900 was discovered near the confluence of Birdflat Creek and the Sustut River in the Sustut Basin (Fig. 1); the bones were found loose in the rubble during construction along the BC Rail line, which has since been abandoned. Fieldwork in the Sustut Basin in 2017 provided strong support for the relocation of the original collection site a few hundred meters from the confluence of the Sustut River and Birdflat Creek (Arbour et al. (in press)); exact GPS coordinates are on file at the Royal BC Museum.
Formation and Age: Tatlatui Member, Tango Creek Formation, Sustut Group. Palynomorphs recovered from the presumed holotype locality included the Maastrichtian marker taxon Pseudoaquilapollenites bertillonites, indicating an age of approximately 68.2–67.2 Ma for the site (Arbour et al. (in press)).
Victoria M. Arbour and David 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