• Geological Age: Jurassic period, Kellaways Bed formation, 165 to 160 million years ago.
• Location: Gloucestershire, Yorkshire, UK.
• Family: Bivalve
• Species: Gryphaea bilobata
Gryphaea bilobata fossil specimens exhibit a wider shape than earlier gryphaea species, these samples are of Jurassic age, found in the Kellaways bed formation in Yorkshire, making them over 160 million years old. They are suitable for educational use and for collectors, as they show evolutionary changes, as well as excellent morphological details such as growth lines on the surface of their bronze coloured shells. Measuring approximately 7 cm in size, these samples will come supplied in a card tray with a label.
Gryphaea bilobata is an extinct species of bivalve belonging the gryphaea group, it is placed later on in the species evolutionary timeline, with early fossil specimens exhibiting a small size shell and oblong shape, where as this particular sub-species appears to be wider and flatter with a more circular shape, indicating a change in shell shape and size over time, potentially due to a change in feeding habits. Like all bivalves, gryphaea bilobatas shells were made up of two parts which were both different sizes, the bottom being smaller than the top. This can be observed in our high quality specimens which also exhibit other morphological details such as the shells hinges and growth lines, the samples also have a dull bronze colouration. approximately 7 cm in length and 5 cm wide, these excellent quality fossils are certainly ideal for serious collectors of marine and mollusc fauna as well as for educational use, to display the changing shape of fauna over geological time. Specimens will come supplied in a card tray with an information label.