An unusual 'shovel-billed' dinosaur with trophic specializations from the early Campanian of Trans-Pecos Texas, and the ancestral hadrosaurian crest
Prieto-Marquez, Albert (Institut Català de Paleontologia Miquel Crusafont)
Wagner, Jonathan R. (Texas Tech University. Department of Geosciences)
Lehman, Thomas (Texas Tech University. Department of Geosciences)
Universitat Autònoma de Barcelona

Data:	2019
Resum:	We describe a new genus and species of hadrosaurid dinosaur, Aquilarhinus palimentus, from the lower shale member of the Aguja Formation (lower Campanian) of Big Bend National Park, south-western Texas. This species is characterized by several autapomorphies of the facial skeleton and mandible, including a crest composed of broadly arched nasals. Notably, the symphyseal processes of the dentary are elongated and reflected dorsally, causing the dentaries to meet with a 'W'-shaped anterior profile. A hypothesized shovel-shaped 'bill', associated with widening of the skull, in A. palimentus might have been used in shovelling out and scooping up semiaquatic vegetation. This animal is otherwise superficially similar to kritosaurins like Gryposaurus but differs in the retention of key plesiomorphic character states in the maxilla and jugal. Phylogenetic analysis reveals Aquilarhinus to be a non-saurolophid hadrosaurid allied to Latirhinus from the late Campanian of Mexico, which bears a similar broadly arched nasal. The recognition of this lineage adds to the diversity of non-saurolophid hadrosaurids and points to the existence of a hitherto unknown diversity of 'duck-billed' dinosaurs outside of the saurolophine-lambeosaurine radiation. Cranial crests were ancestral for early hadrosaurids and evolved before the saurolophid radiation. Ancestrally, crests were 'solid', and consisted of arched nasals. These were retained among kritosaurins and subsequently modified into the diverse crest morphologies observed among derived saurolophines. Lambeosaurine 'hollow-crested' crest morphology departed from the ancestral, 'solid-crested' pre-saurolophid condition early following the origin of that clade.
Ajuts:	Ministerio de Economía y Competitividad RYC-2015-17388 Ministerio de Economía y Competitividad CGL2016-73230-P
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Dinosauria ; Hadrosauridae ; Phylogeny ; Evolution ; Cretaceous ; North America
Publicat a:	Journal of systematic palaeontology, Vol. 18, Issue 6 (2020) , p. 461-498, ISSN 1478-0941

DOI: 10.1080/14772019.2019.1625078

Postprint 88 p, 17.2 MB

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