Fred Ruhe
Well-known member
Ryan Marek, Peter Falkingham & Karl Bates, 2018
The surrogate arm: analysing the role of regionalisation in the variation of the avian neck
Progressive Palaeontology 2018 Abstracts Book
Free pdf: https://www.palass.org/sites/default...act book.pdf
Abstract: https://www.palass.org/sites/default...act book.pdf
Acting as a surrogate forelimb, the avian neck allows for the head to perform environmental manipulation tasks usually accompanied by the forelimbs, which are primarily adapted for flight in birds. This additional selection pressure on the cervical system has led to a vast array of neck morphologies in modern avians, yet no systematic study of this variation has occurred, owing to fluctuating cervical counts. Hox genes regulate axial regionalisation in vertebrates and the number of cervical regions is fixed within a group of vertebrates. Thus, studying cervical regionalisation overcomes problems associated with varying cervical counts. Using a combination of 3D geometric morphometrics and Phenotypic Trajectory Analysis this study assesses the number, size and shape of cervical regions amongst a diverse selection of extant birds. Results support 5 cervical regions within all birds. The anterior- and posterior-most regions (supporting the head and neck as a whole) show little change in region size, yet the middle 3 regions vary enormously in size. Further analysis reveals that region size is associated with neck length, with regions 2 and 4 responsible for neck elongation in birds. Whilst region size shows little correlation with ecology (diet and flight style), Phenotypic Trajectory Analysis reveals that mean region shape appears significantly correlated with both diet and flight style amongst modern birds. Not only have birds evolved an extra cervical region (5 compared to the 4 of ancestral archosaurs), the variation within each region has allowed for the diverse neck morphology seen throughout Aves.
Enjoy,
Fred
The surrogate arm: analysing the role of regionalisation in the variation of the avian neck
Progressive Palaeontology 2018 Abstracts Book
Free pdf: https://www.palass.org/sites/default...act book.pdf
Abstract: https://www.palass.org/sites/default...act book.pdf
Acting as a surrogate forelimb, the avian neck allows for the head to perform environmental manipulation tasks usually accompanied by the forelimbs, which are primarily adapted for flight in birds. This additional selection pressure on the cervical system has led to a vast array of neck morphologies in modern avians, yet no systematic study of this variation has occurred, owing to fluctuating cervical counts. Hox genes regulate axial regionalisation in vertebrates and the number of cervical regions is fixed within a group of vertebrates. Thus, studying cervical regionalisation overcomes problems associated with varying cervical counts. Using a combination of 3D geometric morphometrics and Phenotypic Trajectory Analysis this study assesses the number, size and shape of cervical regions amongst a diverse selection of extant birds. Results support 5 cervical regions within all birds. The anterior- and posterior-most regions (supporting the head and neck as a whole) show little change in region size, yet the middle 3 regions vary enormously in size. Further analysis reveals that region size is associated with neck length, with regions 2 and 4 responsible for neck elongation in birds. Whilst region size shows little correlation with ecology (diet and flight style), Phenotypic Trajectory Analysis reveals that mean region shape appears significantly correlated with both diet and flight style amongst modern birds. Not only have birds evolved an extra cervical region (5 compared to the 4 of ancestral archosaurs), the variation within each region has allowed for the diverse neck morphology seen throughout Aves.
Enjoy,
Fred
