Gryphaea
Encyclopedia
Gryphaea, common name
Devil's toenails, is a genus
of extinct oyster
s, marine
bivalve mollusks in the family
Gryphaeidae
.
These fossil
s range from the Jurassic
to the Cretaceous
periods. They are particularly common in many parts of Britain.
These oysters lived on the sea bed in shallow waters, possibly in large colonies. The complete fossil
s consist of two articulated valves: a larger gnarly-shaped shell (the "toenail") and a smaller, flattened shell, the "lid". The soft parts of the animal occupied the cavity between the two shells, just like modern oysters. The shells also feature prominent growth bands. The larger, curved shell sat within the mud on the sea floor. These shells are sometimes found in fossil plates along with turritella, clams, and some times sharks' teeth and fossilized fish scales.
A classic location to find these fossils is Redcar
on the northeast coast of England. There used to be a common folk belief that carrying one of these fossils could prevent rheumatism
. They are also in abundance in the state of Kansas in riverbeds and cliffs, and are easy to collect and find.
The name "Devil's toenail" is also used for some fossil species of the genus Exogyra
, which is in the same family (Gryphaeidae) as Gryphaea.
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
Devil's toenails, is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of extinct oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s, marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
bivalve mollusks in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Gryphaeidae
Gryphaeidae
Gryphaeidae, common name the foam oysters or honeycomb oysters, is a family of marine bivalve mollusks, related to the true oysters.-Taxonomy:...
.
These fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s range from the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
to the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
periods. They are particularly common in many parts of Britain.
These oysters lived on the sea bed in shallow waters, possibly in large colonies. The complete fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s consist of two articulated valves: a larger gnarly-shaped shell (the "toenail") and a smaller, flattened shell, the "lid". The soft parts of the animal occupied the cavity between the two shells, just like modern oysters. The shells also feature prominent growth bands. The larger, curved shell sat within the mud on the sea floor. These shells are sometimes found in fossil plates along with turritella, clams, and some times sharks' teeth and fossilized fish scales.
A classic location to find these fossils is Redcar
Redcar
Redcar is a seaside resort in the north east of England, and a major town in the unitary authority of Redcar and Cleveland in the ceremonial county of North Yorkshire. It lies east-northeast of Middlesbrough by the North Sea coast...
on the northeast coast of England. There used to be a common folk belief that carrying one of these fossils could prevent rheumatism
Rheumatism
Rheumatism or rheumatic disorder is a non-specific term for medical problems affecting the joints and connective tissue. The study of, and therapeutic interventions in, such disorders is called rheumatology.-Terminology:...
. They are also in abundance in the state of Kansas in riverbeds and cliffs, and are easy to collect and find.
The name "Devil's toenail" is also used for some fossil species of the genus Exogyra
Exogyra
Exogyra is an extinct genus of bivalve mollusks in the family Gryphaeidae, the foam oysters or honeycomb oysters . These bivalves grew cemented by the right valve, the left or upper valve is flatter and the beak is curved to one side. Exogyra lived on solid substrates in warm seas....
, which is in the same family (Gryphaeidae) as Gryphaea.