Elginerpeton
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| Elginerpeton pancheni Ahlberg, 1995 |
Elginerpeton is a fossil dating from the Upper Frasnian (Late Devonian) of Scat Craig, Scotland. It was originally identified as an "unidentified sarcopterygian." But a reevaluation of the early 1990s by Per Ahlberg demonstrated that it was an early tetrapod. Indeed, Elginerpeton and the closely related Obruchevichthys are the two oldest tetrapods known from skeletal material.
The known remains of Elginerpeton fragments from the shoulder and hip, a femur (upper hind limb), tibia (lower hind limb), and fragments from the upper and lower jaw. Another element that may be a humerus (upper forelimb) is also associated with this tetrapod. Extrapolations suggest that the animal was 1.5 m (5 ft) in length.
The jaw of this animal exhibits a mosaic of elpistostegelian fish and tetrapod features. The hip and limbs share features with Ichthyostega while the shoulder is more similar to those of Hynerpeton or Tulerpeton. Unfortunately, no feet (or fish-like fins) were recovered. Consequently, it's unclear whether Elginerpeton is more closely allied with the Panderichthys or with other early tetrapods. In addition, Elginerpeton and its contemporary, Obruchevichthys, share unique features that separate them from the Famennian tetrapods. The front of the skull is narrower than in either osteolepidid lobe-finned fishes and other early tetrapods, and the total cranial length is much longer. Elginerpeton and Obruchevichthys may represent a distinct and presumably short-lived radiation that diverged prior to the emergence of other tetrapods. Associated fauna include a placoderm (Bothriolepis), acanthodians, a lungfish, porolepiform lobe-fins and jawless hererostracans.
