Avaceratops
| Avaceratops | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Speculative life reconstruction of Avaceratops |
||||||||||||
| Temporal occurrence | ||||||||||||
| Upper Cretaceous (late Campanium ) | ||||||||||||
| 76.4 to 72 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Avaceratops | ||||||||||||
| Dodson , 1986 | ||||||||||||
| Art | ||||||||||||
|
||||||||||||
Avaceratops is a little known genus of pelvic dinosaurs from the group of Ceratopsidae within the Ceratopsia .
features
From Avaceratops far only two are poorly preserved skull and a partially preserved body skeleton known. The finds come from subadult (half-grown) animals that were around 2.5 meters long - the length of the adult animals is not known.
The physique resembled that of the rest of the Ceratopsidae with its sturdy trunk, strong limbs and massive head. The nasal bone and the postorbital have not been preserved, so no precise information can be given about the horns of the nose or the ocular horns. As with all Ceratopsidae, the neck shield was formed from the parietal and scaled bones . It was very short compared to other Ceratopsidae.
Discovery and naming
The fossil remains of Avaceratops were found in the Judith River Formation in the US state of Montana and were first described in 1986 . The generic name is derived from "Ava", the first name of the wife of the finder of the remains, and keratops ( Greek for "horny face"), a common part of the Ceratopsia name. The type and only known species is A. lammersi . The finds are dated in the Upper Cretaceous (late Campanium ) to an age of 76 to 72 million years.
Systematics
Avaceratops is one of the Ceratopsidae , the young age of the animals found and the lack of diagnostic key bones make a more precise systematic classification difficult. Dodson et al. (2004) see it as belonging to the Centrosaurinae due to the structure of the scaly bone and the intermaxillary bone . Another study, however, comes to the conclusion that Avaceratops would have assumed a primitive position within the Ceratopsidae and form a transitional form between the two subfamilies Centrosaurinae and Chasmosaurinae .
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Systematic position of Avaceratops according to Evans & Ryan (2015). |
Today Avacerotops is generally assigned to the Centrosaurinae. In 2015, the family tree of the Centrosaurinae was revised by Evans & Ryan (2015) on the occasion of the first description of the Wendiceratops found in Canada . Accordingly, Diabloceratops is the most basal genus and the sister taxon of all other known Centrosaurinae, followed by a common taxon from Nasutoceratops and Avaceratops . In a phylogenetic analysis in 2012, Avaceratops was still considered to be one of the most basal genera of the Centrosaurinae and compared to all other known genera with the exception of Diabloceratops and Xenoceratops .
literature
- Peter Dodson , Catherine A. Forster, Scott D. Sampson: Ceratopsidae. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 494-513.
- Michael J. Ryan, Anthony P. Russell: A new centrosaurine ceratopsid from the Oldman Formation of Alberta and its implications for centrosaurine taxonomy and systematics. In: Canadian Journal of Earth Sciences. Vol. 42, No. 7, 2005, ISSN 0008-4077 , pp. 1369-1387, here p. 1384, sheet 16, doi : 10.1139 / e05-029 , digital copy (PDF; 1.9 MB) ( Memento from 25 February 2012 in the Internet Archive ).
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 264, online ( memento of the original from July 13, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. .
- ^ Paul Penkalski, Peter Dodson: The morphology and systematics of Avaceratops, a primitive horned dinosaur from the Judith River Formation (Late Campanian) of Montana, with the description of a second skull. In: Journal of Vertebrate Paleontology. Vol. 19, No. 4, 1999, ISSN 0272-4634 , pp. 692-711, doi : 10.1080 / 02724634.1999.10011182 .
- ↑ David C. Evans , Michael J. Ryan : Cranial Anatomy of Wendiceratops pinhornensis gen. Et sp. nov., a Centrosaurine Ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation. PLOS ONE 10 (7): e0130007. doi : 10.1371 / journal.pone.0130007 .
- ↑ Michael J. Ryan, David C. Evans, Kieran M. Shepherd: A New Ceratopsid from the Foremost Formation (Middle Campanian) of Alberta. In: Canadian Journal of Earth Sciences , Vol. 49, No. 11, 2012, ISSN 0008-4077 , pp. 1251-1262, doi : 10.1139 / e2012-056 .
