Cedarpelta

***Cedarpelta*** is an extinct genus of herbivorous basal ankylosaurid ankylosaur, based on material recovered from the Lower Cretaceous of North America. The skull lacks extensive cranial ornamentation, a trait which has been interpreted as plesiomorphic for ankylosaurs.

*Cedarpelta* was a large ankylosaurian. In 2010, Gregory S. Paul indicated a body length of 7 metres and a weight of 5 tonnes.[4] Kenneth Carpenter estimated it smaller at 5 metres.[3] Thomas Holtz gave a higher estimation at 9 meters suggesting that it was rivaling *Ankylosaurus*.[5]

Carpenter *et al.* (2001) established several distinguishing traits of *Cedarpelta*. The body of the praemaxilla, the front snout bone, is short in front of its nasal branch. The outer sides of the two praemaxillae run more parallel compared to the snouts of later forms which are strongly diverging to behind. The cutting edge of the bone core of the upper beak is limited to the front of the praemaxilla. Each praemaxilla has six (conical) teeth. The quadrate, and with it the entire back of the skull, is inclined to the front. The head of the quadrate is not fused with the paroccipital process, contrary to the situation in *Shamosaurus*. The neck of the occipital condyle is long and sticking out to behind, like with nodosaurids, not obliquely to below as in typical ankylosaurids. The *tubera basilaria*, appending processes of the rear lower braincase, form a large wedge directed to below. The pterygoid is elongated from the front to the rear and has a saddle-shaped process on its outer edge oriented to behind and sideways. The coronoid process of the rear lower jaw has an oval process at the inside. The straight ischium has a knob-shaped boss at the inside near the pubic pedicle.[2]

*Cedarpelta* shows a mix of basal ("primitive") and derived traits. The presence of premaxillary teeth is a plesiomorphic character because it is inherited from earlier Ornithischia. In contrast, closure of the opening on the side of the skull behind the orbit, the lateral temporal fenestra, is an advanced, derived (apomorphic) character only known in ankylosaurid ankylosaurians.[2]

Two skulls are known, and the skull length for *Cedarpelta* is estimated to have been roughly 60 centimetres (24 in). One of the *Cedarpelta* skulls was found disarticulated, a first for an ankylosaur skull, allowing paleontologists a unique opportunity to examine the individual bones instead of being limited to an ossified unit. The skull is relatively elongated and does not show a strongly appending beak. Of the conical premaxillary teeth, the first is the largest. The maxilla bears eighteen teeth. The eye socket is surrounded by the lacrimal, a single supraorbital and a large postorbital, excluding the prefrontal and the jugal from the orbital rim. The postcranial skeleton was in 2001 not described in any detail.[2]

The skulls, though of large and thus not juvenile individuals, do not show a distinctive pattern of fused *caputegulae*, head tiles. This inspired Carpenter to propose an alternative hypothesis of ankylosaur skull osteoderm formation. Formerly, it had been assumed that such armour plates were either formed by direct skin ossification into distinct scutes which later fused to the skull (the more popular theory), or by a reaction of the skull bones to the pattern of overlying scales. The lack of a clear pattern in *Cedarpelta* suggested to Carpenter that the ossification took place in an intermediate layer between the scales and the skull roof itself, which he surmised to have been the periosteum.[2]

Appearance: Dull green for skin.