This Specimen has been sold.
Jurassic Ammonite & Petrified Wood Association - Dorset, England
This is a gorgeous association of ammonite fossils and petrified wood within a concretion, collected from the Lyme Regis region of England. The largest ammonite (Asteroceras confusum) is 1.7" wide and has a bite mark from a predator. The smallest ammonites are of the species Promicroceras planicosta. The preparation of the petrified wood is excellent and is centered across the middle of the specimen. It comes with a metal/acrylic display stand.
Ammonites were predatory mollusks that resembled a squid with a shell. These cephalopods had eyes, tentacles, and spiral shells. They are more closely related to a living octopus, though the shells resemble that of a nautilus. Ammonites appeared in the fossil record about 240 million years. The last lineages disappeared 65 million years ago at the end of the Cretaceous.
Petrified wood is the name given to wood that has been turned into stone (fossilized) through the process of permineralization. All of the organic matter becomes replaced by minerals, while much of the original structure such as tree rings in retained. For this to happen the wood needs to be buried in an environment both low in oxygen (preventing decomposition) and with flowing, mineral-laden water. The coloration is due to the various minerals that are present during fossilization. For example red colors are due to iron compounds, greens due to copper, etc.
Asteroceras confusum, Promicroceras planicosta & Unidentified Wood
Black Ven, Charmouth, Lyme Regis, Dorset, England
Lower Lias, Obtusum Zone
Entire specimen 9.7 x 7.1"