POLYDACTYLY IN THE EARLIEST KNOWN TETRAPOD LIMBS
POLYDACTYLY IN THE EARLIEST KNOWN TETRAPOD LIMBS
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DOI：
10.1038/347066a0
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发表时间：
1990-09-06
期刊：
影响因子：
64.8
通讯作者：
CLACK, JA
中科院分区：
文献类型：
--
作者：
COATES, MI;CLACK, JA
NEW specimens of the earliest known tetrapod limbs shows them to be polydactylous. The forelimb ofAcanthostegahas eight digits and the hindlimb ofIchthyostegahas seven. Both of these come from the Upper Devonian of East Greenland, complementing the only other known Devonian tetrapod limb, that ofTulerpetonfrom Russia1, which has six digits. The morphology of the specimens suggests that limbs with digits may have been adaptations to an aquatic rather than a terrestrial environment. The pattern of digits corresponds to a recently proposed model for limb development2in which digit number is unspecified, rather than earlier models3–10which are rejected because they postulate a fixed number of elements in the ancestral limb. We challenge pentadactyly as primitive for tetrapods3,11. The form of these limbs suggests early specialization in the evolution of the tetrapod limb bud.
