|Crinoid (Sea Lily) with Dapedium Fish Scales & Pecten Bivalves
from Fretherne, Gloucestershire, England
185 Million Years, Middle Jurassic
Height - 3.9 cm
Width - 10.5 cm
Length - 15 cm
Pentacrinites is an extinct genus of Crinoid, also commonly known as Sea Lily which lived from the Middle Triassic to the Eocene Period of Asia, Europe, North America and New Zealand.
Their stems are pentagonal to star-shaped in cross-section and are the most commonly preserved parts. Pentacrinites are commonly found in the Pentacrinites Bed of the Early Jurassic of Lyme Regis in Dorset, England.
Pentacrinites can be recognized by the extensions (or cirri) all around the stem, which are long, unbranching, and of increasing length further down, the very small cup and 5 long freely branching arms.
Pecten is a genus of large scallops or saltwater clams, marine bivalve mollusks in the family Pectinidae.
This genus is known in the fossil record from the Cretaceous period to the Quaternary period (age range: from 70.6 to 0.012 million years ago.). Fossil shells within this genus have been found all over the world.
Dapedium is an extinct genus of primitive neopterygian ray-finned fish.
The first-described finding was an example of D. politum, found in the Lower Lias of Lyme Regis, on the Jurassic Coast of England by William Elford Leach, (2 February 1791 – 25 August 1836) an English zoologist and marine biologist)
Dapedium lived in the late Triassic and Jurassic periods.
The various species of Dapedium ranged from 9 to 40 centimetres (3.5 to 15.7 in) long, and all had an oval to near-circular body. The skin was covered with thick, rhomboid, ganoid (enamel-like) scales. The smallest species so far found is D. noricum.
The skull was armoured with bony dermal plates, which were especially plentiful in the orbital region. These bones bore irregular tubercles. The small pectoral and pelvic fins, along with the extended dorsal and anal fins formed a functional unit with the tail. The tail was short and stout, providing the power for a sudden change in direction while the fish was swimming.
The upper jaw of Dapedium was moveable and could protrude from the mouth, enabling a wider gape to capture larger prey.