Whatcheeria
Encyclopedia
Whatcheeria is an extinct genus
of early tetrapod
from the Early Carboniferous of Iowa
. Fossils have been found in 340 million year old fissure fill deposits in the town of Delta
. The type species
W. deltae was named in 1995. It is classified within the family Whatcheeriidae
along with the closely related Pederpes
.
traits. It shares with earlier stem tetrapods a series of lateral line
s across the skull, rows of teeth on the palate
, and small Meckelian foramina
across the surface of the lower jaw. It has a cleithrum
, a bone in the pectoral girdle that extends from the scapula
. The cleithrum once attached to the skull in lobe-finned fish, the ancestors of tetrapods, but detached to allow the neck to move freely.
Whatcheeria grew to about 1 metres (3.3 ft) long. The skull is deep and the snout is pointed. A hole on the top of the skull behind the eyes called the parietal foramen
is relatively large in Whatcheeria. The bones on the skull surface are unusually smooth, unlike the pitted skulls of many other early tetrapods. In front of the eye socket, the prefrontal bone
forms a prominent ridge. The prefrontal also projects downward to cover a possible sinus
.
of Whatcheeria, W. deltae, was named in 1995. Whatcheeria is named after What Cheer, Iowa
, the hometown of the man who discovered the first skeletons of the animal. The species is named after Delta, Iowa
, the location where the fossils were uncovered. Hundreds of tetrapod fossils were found in the locality, and the majority of these specimens are thought to belong to Whatcheeria. Fish and plant fossils have also been found in the same deposits. Several other tetrapods, including temnospondyls and embolomeres, are known from the Delta locality.
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 early tetrapod
Tetrapod
Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...
from the Early Carboniferous of Iowa
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
. Fossils have been found in 340 million year old fissure fill deposits in the town of Delta
Delta, Iowa
Delta is a city in Keokuk County, Iowa, United States. The population was 410 at the 2000 census.-Geography:Delta is located at .According to the United States Census Bureau, the city has a total area of , all of it land....
. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
W. deltae was named in 1995. It is classified within the family Whatcheeriidae
Whatcheeriidae
Whatcheeriidae was a family of tetrapods which lived in the Mississippian sub-period, a subdivision of the Carboniferous period. It contains the genera Pederpes and Whatcheeria...
along with the closely related Pederpes
Pederpes
Pederpes is an extinct genus of early Carboniferous tetrapod, dating from the Tournaisian age . Pederpes contains one species, P...
.
Description
Whatcheeria possesses a mixture of both primitive and derivedDerived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
traits. It shares with earlier stem tetrapods a series of lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
s across the skull, rows of teeth on the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
, and small Meckelian foramina
Meckelian groove
The Meckelian groove is an opening in the medial surface of the mandible which exposes the Meckelian cartilage....
across the surface of the lower jaw. It has a cleithrum
Cleithrum
The cleithrum is a membrane bone which first appears as part of the skeleton in primitive bony fish, where it runs vertically along the scapula. Its name is derived from Greek κλειθρον = "key ", by analogy with "clavicle" from Latin clavicula = "little key".In modern fishes, the cleithrum is a...
, a bone in the pectoral girdle that extends from the scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
. The cleithrum once attached to the skull in lobe-finned fish, the ancestors of tetrapods, but detached to allow the neck to move freely.
Whatcheeria grew to about 1 metres (3.3 ft) long. The skull is deep and the snout is pointed. A hole on the top of the skull behind the eyes called the parietal foramen
Parietal foramen
At the back part of the parietal bone and close to the upper or sagittal border is the parietal foramen, which transmits the parietal emissary vein which anastamoses with the superior sagittal sinus, and sometimes a small branch of the occipital artery; it is not constantly present, and its size...
is relatively large in Whatcheeria. The bones on the skull surface are unusually smooth, unlike the pitted skulls of many other early tetrapods. In front of the eye socket, the prefrontal bone
Prefrontal bone
The prefrontal bone is a bone separating the lacrimal and frontal bones in many tetrapod skulls. It first evolved in the sarcopterygian clade Rhipidistia, which includes lungfish and the Tetrapodomorpha. The prefrontal is found in most modern and extinct lungfish, amphibians and reptiles...
forms a prominent ridge. The prefrontal also projects downward to cover a possible sinus
Sinus
- Anatomy :In anatomy, where a sinus is a sac or cavity in any organ or tissue:*Sinus , description of the general term*Paranasal sinuses, air cavities in the cranial bones, especially those near the nose, including:...
.
History
The type speciesType species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of Whatcheeria, W. deltae, was named in 1995. Whatcheeria is named after What Cheer, Iowa
What Cheer, Iowa
What Cheer is a city in Keokuk County, Iowa, United States. The population was 678 at the 2000 census.- The name What Cheer :When the future What Cheer was founded in 1865, it was named Petersburg for Peter Britton, the settlement's founder. This name was rejected by the Post Office, forcing a...
, the hometown of the man who discovered the first skeletons of the animal. The species is named after Delta, Iowa
Delta, Iowa
Delta is a city in Keokuk County, Iowa, United States. The population was 410 at the 2000 census.-Geography:Delta is located at .According to the United States Census Bureau, the city has a total area of , all of it land....
, the location where the fossils were uncovered. Hundreds of tetrapod fossils were found in the locality, and the majority of these specimens are thought to belong to Whatcheeria. Fish and plant fossils have also been found in the same deposits. Several other tetrapods, including temnospondyls and embolomeres, are known from the Delta locality.