Comparison between axial skeletons of primitive tetrapods suggests that plesiomorphic fish-like morphologies were re-patterned in a cranio-caudal direction with the emergence of tetrapod vertebral regionalisation.
Biological reviews of the Cambridge Philosophical…
1 May 2003
TLDR
A deep split of early tetrapods between lissamphibian‐ and amniote‐related taxa is detected and is indicated by the results of the original parsimony run ‐ as well as those retrieved from several other treatments of the data set.
New palaeontological evidence is presented that the neopterygian crown radiation is a Palaeozoic event, and it is demonstrated that conflicts between molecular and morphological data for the age of the Neopterygii result, in part, from missing fossil data.
It is shown that major vertebrate clades suffered acute and systematic effects centered on the Hangenberg extinction involving long-term losses of over 50% of diversity and the restructuring of vertebrate ecosystems worldwide.
Tests of different crown topologies show that placement of amphibians within lepospondyls is not a significantly worse fit for the whole character set than a close temnospondyl‐lissamphibian relationship, and the latter phylogenetic hypothesis best captures the most coherent assembly of derived lissampshibian apomorphies.
This work describes a new, parsimony-based method, which it is called Parsimov, that greatly increases the utility of the event-pair method for inferring instances of sequence heterochrony.
A marine/estuarine fossil lamprey from the Famennian (Late Devonian) of South Africa is reported, the identity of which is established easily because many of the key specializations of modern forms are already in place, evidence that agnathans close to modern lampreys had evolved before the end of the Devonian period.
A new description of the Acanthodes braincase is presented, yielding new details of external and internal morphology, notably the regions surrounding and within the ear capsule and neurocranial roof that contribute to a new reconstruction that, unexpectedly, resembles early chondrichthyan crania.
A cladistic analysis indicates that Tulerpeton is a reptiliomorph stem-group amniote and the earliest known crown-group tetrapod: Acanthostega and Ichthyostega are successively more derived plesion stem- group tetrapods and do not consititute a monophyletic ichthyostegalian radiation.
A genus–level supertree for early tetrapods is built using a matrix representation of 50 source trees, and a second analysis, which excludes source trees superseded by more comprehensive studies, supports a deep phylogenetic split between lissamphibian and amniote total groups.