Chasmosaurinae

Skeletal reconstruction of Pentaceratops Sternbergii

  • West North America ( Laramidia )

The Chasmosaurinae (also Ceratop ( s ) inae ) are a taxon ( a systematic group) of the dinosaurs. Together with the Centrosaurinae they form the group of Ceratopsidae within the ceratopsians.

Features

The Chasmosaurinae moved away like all Ceratopsidae quadruped ( four legged ), the forelimbs were much shorter than the hind legs. The extremities were generally strong, the body is stocky.

The skull was large and bulky and had a pointed snout. This was made ​​like all ceratopsians from the Rostralknochen ( in front of the upper jaw ) and the Praedentale ( in front of the lower jaw). The dentition was like all Ceratopsidae from tooth batteries, which are arranged in rows of teeth that have been replaced after wear through the following tooth.

The most striking differences to the Centrosaurinae existed in the horns and neck plate. The nasal horn was greatly reduced, in return, the supraorbital horns were significantly prolonged. The neck shield, which was formed as in all higher ceratopsians from the parietal and squamosal was mostly long - sometimes up to 100 percent of the actual length of the skull - and had large holes - only when he Triceratops was shortened and closed.

The length of the skull, including the neck shield reached at Pentaceratops and Torosaurus over two meters, these are the longest known skull under all land-dwelling animals. The bony structures at the edge of the shield ( Epoccipitalia ) were at best simple knobs and no spines as in some Centrosaurinae.

Distribution and systematics

As with all Ceratopsidae also fossil evidence of Chasmosaurinae found only in the western part of North America. The west of the continent was an island that is called Laramidia during most of the Cretaceous. This Paläoinsel was isolated by a shallow sea, the Western Interior Seaway, therefore Ceratopsiden on Laramidia were limited, so there were endemic. Fossil remains of this dinosaur group known only from the Upper Cretaceous ( Campanian to mid Maastrichtian ) and thus about 80 to 66 million years old.

The following classes will be provided to Chasmosaurinae:

Since the material of Ceratops, after the Ceratopsidae be named, is not sufficient for an accurate determination of systematic, Lawrence Lambe named this group in 1915 after Chasmosaurus. Belonging to this group of Triceratops was only later recognized because this dinosaur is significantly different with his short neck shield of the other members.

Mya (unit) Cerapoda Rostral bone Digital Object Identifier
172867
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