Elrathia Kingii Trilobite Fossil From Utah
Middle Cambrian Period- C. 505 Million Years Ago
Order to which the fossil belongs: Ptychopariida
Name of which the family belongs: Ptychoparioidea
Informal name of the fossil: Trilobite
Trilobites are a fossil group of extinct marine arachnomorph arthropods that form the class Trilobite, one of the earliest known groups of arthropods. The name originates from their division into three longitudinal lobes, consisting of a raised central lobe also known as the axis, with two slightly flatter pleural lobes either side. Trilobites also have a head shield known as the cephalon, and on the axial region of the head shield (glabella) there were cheeks either side and well-developed eyes.
The head of the Elrathia is small compared to its thorax, which consists of up to thirteen narrow segments, each would have had a limb, but these are rarely preserved. The glabella is of a small flowerpot shape with centrally placed eyes and triangular genal spines which are short. The tail with twice as wide as it is long with a well defined axis which extends far back. A trilobite would have probably roll up their external skeletons to protect themselves in defence. The typical length of a Elrathia is 2cm.
A nice example of a Elrathia trilobite fossil on a stone matrix with crisp definition.
Size: 76mm x 102mm