Fossils and their interpretations essay Example | Topics and Well Written Essays - 1000 words

Fossils and their interpretations - Essay Example Several paleontologists have managed to collect close to 2000 Eusthenopteron specimens, which have been effective at providing room for the detailed study of this species. Basing on the anatomy, Eusthenopteron shares several unique features that are common with some earliest known tetrapods. The largest individual was capable of growing up to 1.8 meters in length, while is also shares the similar pattern of the skull roofing bones with other forms, such as Ichthyostaga and Acanthostega. Eusthenopteron like any other tetrapodomorph fisheries had internal nostrils, which are only found in the land animals. From this fossil, one can develop a thesis that all creatures developed from a transition of other creatures. The image of this fossil is as shown below; Figure: Eusthenopteron foordi. University Museum of Zoology Cambridge specimen GN. 786. Scale bar is 10 millimeters. Photograph by JAC Pathologists Jennifer A. Clack (2002) believes that Eusthenopteron showed some characteristics of crawling across the dry landscape with the help of its fore fins while moving around. This fossil also shows that it had labyrinthodont teeth, which are characterized by the infolded enamel, which also characterizes the rest of earliest known tetrapods as well. ... The appendicular long bones of this fossil shows that it had some epiphyseal growth plates that were essential at allowing substancial longitudinal growth through the endochondral ossification, as similar to the case of tetrapod long bones. The genus has six appendicular bones that also occur in tetrapods and are thus a synapomorphy of the large clade of sarcopterygians, which is also possibly the subclass Tetrapodomorpha. This genus also lacks some superficial odontodes on its elasmoid scales, which are composed of the dentine and enamel. The lack of such similarities implies that there is a synapornorphy with more crownward tetrapodomorphs. The genus Eusthenopteron also differs from the later Carboniferous tetrapods basing on the apparent absence of some recognized larval stage and the definitive metamorphosis. But on the even smallest known specimens of the Eusthenopteron foordi, when it attains a length of 29mm, the lepidotrichia is able to cover all the fins, which on the contra ry do not happen with after metamorphosis occurs in the genera like Polyodon. This has the implication of stating that Eusthenopteron developed directly, with its hatching already managing to attain the general body of the adult species. This therefore implies that Palaeospondylus gunni might not have been the larva of Eusthenopteron. The author responds to these claims about Eusthenopteron with some sort of analysis. There are emerging issues that now, nearly 20 years of which this subject has undergone a renaissance; there is much enriched fossil record to draw implications from. However, much of this recent work is yet to reflect on the popularity of the accounts on this subject. There is some assumption that Devonian tetrapods and the respective close fish relatives originate