Eolambia

Eolambia
	Drawing of Eolambia Caroljonesa ( reconstruction )
Temporal occurrence
	Upper Cretaceous (early Cenomanian )
	100.5 to 96.2 million years
Locations
	Utah , USA ( Cedar Mountain Formation );
Systematics
	Ornithischia
	Ornithopoda
	Iguanodontia
	Hadrosauroidea
	Eolambia
Scientific name
	Eolambia
	Kirkland , 1998
Art
	Eolambia caroljonesa;

Eolambia is a genus ornithopod dinosaur from the group of Hadrosauroidea .

Several fragmentary skeletons of both adults and young animals are known to date; furthermore could embryonic remnants and possible eggshells are described. All remains are from the Cedar Mountain Formation , a rich fossil deposit in the US state of Utah , and are dated to the Early Cretaceous (early Cenomanian , about 100 to 96 million years ago).

The only known species is Eolambia caroljonesa ; The species and genus were first described scientifically in 1998 by James I. Kirkland .

features

So far, three incomplete skulls are known that suggest a skull length of up to one meter. In contrast to the lambeosaurines , the nasal and intermaxillary bones did not form a crest. There were 32 tooth sockets on each side of the upper jaw, while in the lower jaw there were probably fewer than 30 on each of the holotype specimens. Under each “active” tooth there were at least two replacement teeth, at least in the lower jaw. The tooth crowns are characterized by a single central incisal edge and were 3.3 cm high and 1.7 cm wide for the largest teeth. The residual skeleton (postcranium) is characterized by at least seven sacral vertebrae and high vertebral spines on the anterior caudal vertebrae. The front legs were massive and long compared to those of other genera.

Systematics

At first, James Kirkland described Eolambia as a representative of the Lambeosaurinae , a subfamily within the Hadrosauridae , which is characterized by striking head crests. Kirkland justified his assignment with various common features ( synapomorphies ), which are found in particular on the intermaxillary bone. Later authors classified Eolambia outside the Hadrosauridae as the original representative of the Hadrosauroidea. A 2001 re-examination of the Eolambia fossils found that many of the lambeosaurin-like characteristics identified by Kirkland were indeed misinterpretations. This study sees Eolambia as a close relative of Probactrosaurus .

Research history and naming

In 1993, Carole and Ramal Jones discovered severely weathered fossil bones in northwestern San Rafael Swell (east of Castle Dale , Utah). They gave the fossils to Donald Burge, the director of the Prehistoric Museum in Price , who then organized an excavation that uncovered a fragmentary skeleton including skull bones. The skeleton was just below the surface, which is why many bones were damaged by roots. The skeleton of a new genus of nodosaurs was found nearby . The site belongs to the Mussentuchit member, a layer member of the Cedar Mountain Formation , and is known today as the "Carol Site" in honor of the discoverer.

The paleontologist James Kirkland took over the scientific processing of the new dinosaur. Kirkland examined other skeletons from the same area that had previously been kept in the collection of the Oklahoma Museum of Natural History and found that they could also be assigned to this genus. Kirkland named the new species and genus Eolambia caroljonesa . The generic name Eolambia means something like "early lambeosaurs" and underlines the very early appearance of this dinosaur , which Kirkland assigned to the subfamily Lambeosaurinae . The second part of the species name, caroljonesa , honors Carole Jones, who discovered the site with the type specimen.

Before it was scientifically described, the genus was given the informal name "Eohadrosaurus".

supporting documents

^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 294, online .
↑ ^a ^b ^c ^d ^e ^f James Ian Kirkland : A new hadrosaurid from the upper Cedar Mountain Formation (Albian-Cenomanian: Cretaceous) of eastern Utah - the oldest known hadrosaurid (lambeosaurine?) In: Spencer G. Lucas, James I. Kirkland , John W. Estep (Ed.): Lower and Middle Cretaceous terrestrial ecosystems (= New Mexico Museum of Natural History and Science. Bulletin. Vol. 14, ISSN 1524-4156 ). New Mexico Museum of Natural History and Science, Albuquerque NM 1998, pp. 283-295, online .
↑ Eolambia. In: The Paleobiology Database. Retrieved September 12, 2014 .
^ Jason J. Head: A reanalysis of the phylogenetic position of Eolambia caroljonesa (Dinosauria, Iguanodontia). In: Journal of Vertebrate Paleontology. Vol. 21, No. 2, 2010, ISSN 0272-4634 , pp. 392-396, doi : 10.1671 / 0272-4634 (2001) 021 [0392: AROTPP] 2.0.CO; 2 .

Web links

Early Cretaceous Dinosaurs of Utah , Utah Geological Survey
Eolambia , Natural History Museum in London

[paul_10-1] Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 294, online .

[kirtland_94-2] ↑ ^a ^b ^c ^d ^e ^f James Ian Kirkland : A new hadrosaurid from the upper Cedar Mountain Formation (Albian-Cenomanian: Cretaceous) of eastern Utah - the oldest known hadrosaurid (lambeosaurine?) In: Spencer G. Lucas, James I. Kirkland , John W. Estep (Ed.): Lower and Middle Cretaceous terrestrial ecosystems (= New Mexico Museum of Natural History and Science. Bulletin. Vol. 14, ISSN 1524-4156 ). New Mexico Museum of Natural History and Science, Albuquerque NM 1998, pp. 283-295, online .

[paleodb-3] Eolambia. In: The Paleobiology Database. Retrieved September 12, 2014 .

[head_011-4] Jason J. Head: A reanalysis of the phylogenetic position of Eolambia caroljonesa (Dinosauria, Iguanodontia). In: Journal of Vertebrate Paleontology. Vol. 21, No. 2, 2010, ISSN 0272-4634 , pp. 392-396, doi : 10.1671 / 0272-4634 (2001) 021 [0392: AROTPP] 2.0.CO; 2 .