Polacanthidae
Encyclopedia
Polacanthidae is a group of ankylosaurs
. Polacanthids are late Jurassic to early Cretaceous in age, and Kirkland observed they appeared to become extinct about the same time a land bridge
opened between Asia and North America.
Polacanthids were somewhat more lightly armoured than more advanced ankylosaurids and nodosaurids. Their spikes were made up of thin, compact bone with less reinforcing collagen than in the heavily armoured nodosaurids. The relative fragility of polacanthid armour suggests that it may have been as much for display as defense.
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...
. Polacanthids are late Jurassic to early Cretaceous in age, and Kirkland observed they appeared to become extinct about the same time a land bridge
Land bridge
A land bridge, in biogeography, is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonise new lands...
opened between Asia and North America.
Polacanthids were somewhat more lightly armoured than more advanced ankylosaurids and nodosaurids. Their spikes were made up of thin, compact bone with less reinforcing collagen than in the heavily armoured nodosaurids. The relative fragility of polacanthid armour suggests that it may have been as much for display as defense.
Taxonomy
- Family Polacanthidae
- GargoyleosaurusGargoyleosaurusGargoyleosaurus is one of the earliest ankylosaurs known from reasonably complete fossil remains. Its skull measures in length, and its total body length is an estimated . It may have weighed as much as...
- GastoniaGastonia (dinosaur)Gastonia is a genus of nodosaurid dinosaur from the Early Cretaceous of North America, around 125 million years ago. Closely related to Polacanthus, it has a sacral shield and large shoulder spikes. It is also the first polacanthine dinosaur to have been mounted for display at the Denver Museum of...
- HoplitosaurusHoplitosaurusHoplitosaurus was a genus of armored dinosaur related to Polacanthus. It was named from a partial skeleton found in the ?Barremian-age Lower Cretaceous Lakota Formation of Custer County, South Dakota. It is an obscure genus which has been subject to some misinterpretation of its damaged remains...
- HylaeosaurusHylaeosaurusHylaeosaurus is the most obscure of the three animals used by Sir Richard Owen to first define the new group Dinosauria, in 1842. The original specimen, recovered by Gideon Mantell from the Tilgate Forest in the south of England in 1832, now resides in the Natural History Museum of London, where...
- MymoorapeltaMymoorapeltaMymoorapelta is an ankylosaur from the Late Jurassic Morrison Formation of western Colorado. The taxon is known from portions of a disarticulated skull, parts of three different skeletons and other postcranial remains...
- PolacanthusPolacanthusPolacanthus, deriving its name from the Ancient Greek poly-/πολυ- "many" and acantha/ακανθα "thorn" or "prickle", was an early armored, spiked, plant-eating ankylosaur from the early Cretaceous period. Early depictions often gave it a very vague head as it was only known from the rear half of the...
- Gargoyleosaurus