The origin of tetrapods (land vertebrates) during the Devonian period, a key event for the terrestrial ecosystem, is illuminated by splendid fossil discoveries but very ill-served by the dominant theoretical framework. This framework has two weaknesses: the persistence of a simplistic evolutionary scenario that has already been falsified, and a failure to properly consider the place of tetrapods in the developing terrestrial ecosystem. The scenario envisages tetrapods evolving from ‘elpistostegids’ like Tiktaalik in an aquatic environment during the Late Devonian, but fails to account for the existence of tetrapod trackways that are older than the elpistostegids, and cannot explain the evolution of structures such as a sacrum (link between pelvis and vertebral column) that lack inherent value for aquatic locomotion. The extraordinary value of the trackways as behavioural records of living animals is ignored. Environmental contexts like ‘flooded forests’ are proposed for the evolution of tetrapods without analysis of the environments where their tracks are preserved. Unless this situation is remedied the subject cannot progress.
To solve these problems, I will combine my world-leading expertise on Devonian tetrapods with the skills of a team of world-class experts on trace fossils, morphometrics, geochemistry, sedimentology, Devonian land plants, and synchrotron tomography. This approach is unprecedented in the study of the origin of tetrapods. We will undertake a bold fieldwork program, coupled with cutting-edge, high-precision, multidisciplinary analysis, which will power the first-ever analysis of the fish-tetrapod transition in a fully elaborated environmental and ecological context. This will at last allow us to fully integrate tetrapods into the vibrant research area of terrestrial ecosystem evolution. We will also search systematically for the still-missing holy grail of early tetrapod research: body fossils contemporary with the earliest tetrapod trackways.
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