Periodic Reporting for period 1 - Dino-Bird Ecology (Tetrapod limb ecomorphology inferring ecology during dinosaur-bird transition)
Berichtszeitraum: 2021-06-01 bis 2023-05-31
Birds are the only living group of dinosaurs and are among the most successful vertebrate groups. The unparalleled Yanliao and Jehol faunas from China are among the most famous fossil sites that produce the oldest birds after Archaeopteryx, living alongside their close dinosaurian relatives. These sites provide unprecedented information about the origin and early evolution of birds. However, traditional methods of study provide only limited information on their anatomy and ecology, presenting a fundamental knowledge gap regarding the dinosaur-bird transition – one of the most important events in vertebrate evolution.
In this project, advanced imaging techniques were applied to capture the 3D data of those exquisite fossil birds and feathered non-avian dinosaurs, to infer their character evolution and ecological traits during the dinosaur-bird transition. This was achieved through statistical comparative analysis of 3D data and ecological traits of extant species, using leading-edge quantitative and biomechanical analyses. This project combined the fossil resources and technique expertise across UK and China, thus highly enhanced the research profile of both countries by both scientific results, and public engagement outreach.
With all the advanced techniques, this project answers the following research questions:
(1) What is the relationship between morphology and ecology traits like diets and habits in extant tetrapods especially birds?
(2) What ecological inferences does fossilized morphology indicate for early birds and their dinosaurian relatives, and their implications about the origin and early diversification of birds?
In this project, advanced imaging techniques were applied to capture the 3D data of those exquisite fossil birds and feathered non-avian dinosaurs, to infer their character evolution and ecological traits during the dinosaur-bird transition. This was achieved through statistical comparative analysis of 3D data and ecological traits of extant species, using leading-edge quantitative and biomechanical analyses. This project combined the fossil resources and technique expertise across UK and China, thus highly enhanced the research profile of both countries by both scientific results, and public engagement outreach.
With all the advanced techniques, this project answers the following research questions:
(1) What is the relationship between morphology and ecology traits like diets and habits in extant tetrapods especially birds?
(2) What ecological inferences does fossilized morphology indicate for early birds and their dinosaurian relatives, and their implications about the origin and early diversification of birds?
This project built up a digital database of foot for birds, with a large sample size of ~90 species across the phylogeny. Digits were segmented and landmarked separately to reveal the most comprehensive and real morphology of foot, thus allows us to address questions about the character evolution and the ecological indications of this important structure, using quantitative methods such as geometric morphometric analyses. The results indicate that the ungual digits and the last non-ungual digits might be the most significant indicators for habits in the foot. The manuscript resulted from this work is under preparation and will be submitted soon. To make the most use of these data and inspire more related future research, all the CT scanning data has been uploaded and made freely available online via Morphosource (www.morphosource.org). The newly segmented 3D models, the landmark data and the R codes will be publicly archived once the manuscript gets published soon.
The project was also expanded to apply these relevant techniques to other structures such as the skull and mandible of both extant and extinct birds. High-resolution synchrotron tomography was conducted on an exquisitely preserved new skull of Jeholornis - one of the earliest-diverging birds, providing a near-complete cranial reconstruction. The possibility that Jeholornis was granivorous was excluded, based on morphometric analyses of the mandible and cranium, and comparisons with the 3D alimentary contents of extant birds. This provides the earliest evidence for fruit consumption in birds, and indicates that birds may have been recruited for seed dispersal during the earliest stages of the avian radiation. This work has been published in eLife (https://elifesciences.org/articles/74751(öffnet in neuem Fenster)).
Based on the data produced above, we also provided a detailed description of the cranial osteology of Jeholornis, confirming the overall plesiomorphic morphology of the skull, with the exception of the more specialized rostrum. Evidence of sensory adaptation suggested that olfaction was an important aspect of Jeholornis ecology. The digitally reconstructed scleral ring suggests a strongly diurnal habit, supporting the hypothesis that early-diverging birds were predominantly active during the day. This work has been published in Zoological Journal of the Linnean Society (https://academic.oup.com/zoolinnean/article/198/1/93/6768673(öffnet in neuem Fenster)).
Following research about the diet of Jeholornis combined our geometric morphometric results from above work and the study of phytoliths, providing evidence of Jeholornis consuming angiosperm leaves of the clade Magnoliales. These results lend further support for early ecological connections among the earliest birds and angiosperms. This work has been published as a preprint in Research Square (https://www.researchsquare.com/article/rs-2557852/v1(öffnet in neuem Fenster)) and has been accepted in Nature Communications.
Despite the stem taxon Jeholornis, this project also investigated the ecology of another important Early Cretaceous avian lineage – Enantiornithes. Drawing inferences from both avian bill proportions and variations in the dental morphology of extinct and extant taxa, we provided quantitative data to support the hypothesis that the Longipterygidae were animalivorous, with greater support for insectivory. This work has been published in PeerJ (https://peerj.com/articles/15139/(öffnet in neuem Fenster)).
This project also made effort to disseminate transferable skills of the quantitative analyses pipeline, i.e. 3D imaging and reconstruction, geometric morphometrics and statistical comparative analysis, to other especially Chinese researchers. Besides the presentations in the international conferences, we have been invited and published an introduction and protocol of geometric morphometrics in a Chinese textbook, while this expertise has been eagerly anticipated in Chinese vertebrate palaeontology (https://bio-protocol.org/exchange/protocoldetail?id=1010664&type=1(öffnet in neuem Fenster)).
Together with all these scientific publications, media release and relevant conference presentations have been made to spread the project results through the whole project period.
The project was also expanded to apply these relevant techniques to other structures such as the skull and mandible of both extant and extinct birds. High-resolution synchrotron tomography was conducted on an exquisitely preserved new skull of Jeholornis - one of the earliest-diverging birds, providing a near-complete cranial reconstruction. The possibility that Jeholornis was granivorous was excluded, based on morphometric analyses of the mandible and cranium, and comparisons with the 3D alimentary contents of extant birds. This provides the earliest evidence for fruit consumption in birds, and indicates that birds may have been recruited for seed dispersal during the earliest stages of the avian radiation. This work has been published in eLife (https://elifesciences.org/articles/74751(öffnet in neuem Fenster)).
Based on the data produced above, we also provided a detailed description of the cranial osteology of Jeholornis, confirming the overall plesiomorphic morphology of the skull, with the exception of the more specialized rostrum. Evidence of sensory adaptation suggested that olfaction was an important aspect of Jeholornis ecology. The digitally reconstructed scleral ring suggests a strongly diurnal habit, supporting the hypothesis that early-diverging birds were predominantly active during the day. This work has been published in Zoological Journal of the Linnean Society (https://academic.oup.com/zoolinnean/article/198/1/93/6768673(öffnet in neuem Fenster)).
Following research about the diet of Jeholornis combined our geometric morphometric results from above work and the study of phytoliths, providing evidence of Jeholornis consuming angiosperm leaves of the clade Magnoliales. These results lend further support for early ecological connections among the earliest birds and angiosperms. This work has been published as a preprint in Research Square (https://www.researchsquare.com/article/rs-2557852/v1(öffnet in neuem Fenster)) and has been accepted in Nature Communications.
Despite the stem taxon Jeholornis, this project also investigated the ecology of another important Early Cretaceous avian lineage – Enantiornithes. Drawing inferences from both avian bill proportions and variations in the dental morphology of extinct and extant taxa, we provided quantitative data to support the hypothesis that the Longipterygidae were animalivorous, with greater support for insectivory. This work has been published in PeerJ (https://peerj.com/articles/15139/(öffnet in neuem Fenster)).
This project also made effort to disseminate transferable skills of the quantitative analyses pipeline, i.e. 3D imaging and reconstruction, geometric morphometrics and statistical comparative analysis, to other especially Chinese researchers. Besides the presentations in the international conferences, we have been invited and published an introduction and protocol of geometric morphometrics in a Chinese textbook, while this expertise has been eagerly anticipated in Chinese vertebrate palaeontology (https://bio-protocol.org/exchange/protocoldetail?id=1010664&type=1(öffnet in neuem Fenster)).
Together with all these scientific publications, media release and relevant conference presentations have been made to spread the project results through the whole project period.
This project applied the cutting-edge quantitative methods to explore the ecomorphology of both living and fossil birds, and is being expanded to cover wider taxa like mammals and squamates. The unique quantitative 3D database generated in this project has theoretical significance and methodological innovation. Besides the already published results above, this publicly assessable database and pipeline will inspire more international researchers and merit more publication in high-impact, cross-disciplinary journals in the future. These data are also being the base of establishing a new finite element model database, with some of the finite element models have been built up based on them. This will enable us to expand the results of this project to test the function-morphology relationship using more interdisciplinary methods together in the future, as well as in wider phylogenetic frame.
The training and two-way transfer of knowledge between the researcher of this project and her hosts in University of Oxford and University of Bristol was very successful, with all the necessary key skills such as 3D visualization, coding, geometric morphometric analysis, finite element model building and analysis obtained well by the researcher. Based on this, the researcher has been making the plan to build her own lab as proposed in this project. The network support across UK, US, Australia and China has been enhanced and expanded for both the researchers and the hosts. Public engagement has also been emphasized through the whole project, with many press releases and two paleontology related popular book published.
The training and two-way transfer of knowledge between the researcher of this project and her hosts in University of Oxford and University of Bristol was very successful, with all the necessary key skills such as 3D visualization, coding, geometric morphometric analysis, finite element model building and analysis obtained well by the researcher. Based on this, the researcher has been making the plan to build her own lab as proposed in this project. The network support across UK, US, Australia and China has been enhanced and expanded for both the researchers and the hosts. Public engagement has also been emphasized through the whole project, with many press releases and two paleontology related popular book published.