Baryonyx
From Greek 'barys' meaning 'heavy' and 'onyx' meaning 'claw', referring to the large, heavy thumb claw that is characteristic of this dinosaur.
Baryonyx is a genus of theropod dinosaur which lived in the Barremian stage of the Early Cretaceous period, about 130-125 million years ago. The first skeleton was discovered in 1983 in the Smokejack Clay Pit, of Surrey, England, in sediments of the Weald Clay Formation, and became the holotype specimen of Baryonyx walkeri, named by paleontologists Alan J. Charig and Angela C. Milner in 1986. The genus name Baryonyx comes from Ancient Greek βαρύς (barús), meaning "heavy" or "strong", and ὄνυξ (ónux), meaning "claw", alluding to the animal's very large claw on the first finger; the specific name, walkeri, refers to its discoverer, amateur fossil collector William J. Walker. The holotype specimen is one of the most complete theropod skeletons from the UK (and remains the most complete spinosaurid), and its discovery attracted media attention. Specimens later discovered in other parts of the United Kingdom and Iberia have also been assigned to the genus, though many have since been moved to new genera.
Diagnosis
- Prenarial rostrum extremely narrow with a spatulate, horizontal expansion at its tip, slightly downturned in lateral view
- Unusually high tooth count (~double typical theropods: dentary 32), crowns lightly fluted lingually with very fine serrations (~7 per mm) on anterior and posterior keels
- Long, strongly opisthocoelous cervical vertebrae with well-developed epiphyses and short neural spines; apposed centra do not produce the typical theropod upward neck curvature
- Humerus with both ends broadly expanded and extremely flattened, offset ~35° against each other, with a massive nearly straight shaft
- Small median knob at posterior end of conjoined nasals, cruciform in dorsal view, with anterior limb drawn forward into a low thin median crest
- At least one pair of exceptionally large ungual phalanges (huge talons), probably on the manus, far exceeding typical theropod ungual proportions
Species
Baryonyx walkeri Charig & Milner, 1986
Type species
Named for William J. Walker, the amateur fossil collector who discovered the holotype specimen in the Smokejack Clay Pit in Surrey, England in 1983.
- Holotype
- NHMUK PV R 9951 , Natural History Museum
- Material
- Conjoined premaxillae, front of left maxilla, conjoined nasals, lacrimal and adjacent bones, frontals, anterior braincase, occiput, left dentary, some post-dentary bones; teeth; axis, most cervicals, some dorsals, one caudal; cervical rib, dorsal ribs, gastralia, chevrons; both scapulae, coracoids, possible clavicle; both humeri, manus phalanges including an extremely large ungual; ilia, pubes, ischium; both femora (partial), left fibula; right calcaneum; distal metatarsals, pes phalanges
- Horizon
- Upper Weald Clay Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
- Locality
- Smokejacks Brickworks, Surrey, United Kingdom
References
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Barker, C. T.; Naish, D.; Gostling, N. J. (2023). Isolated tooth reveals hidden spinosaurid dinosaur diversity in the British Wealden Supergroup (Lower Cretaceous). PeerJ 11: e15453. PeerJ. doi:10.7717/peerj.15453
Gives the type specimen as from "the Barremian Upper Weald Clay Formation of Surrey".
barker2023a - Charig, A. J.; Milner, A. C. (1986). Baryonyx, a remarkable new theropod dinosaur. Nature 324(6095): 359-361. Springer Science and Business Media LLC. doi:10.1038/324359a0 charig1986a
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Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.
Source of the appearance features.
paul2024a