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Enantiornithine osteohistology from Lower Cretaceous + Iberomesornis micro-CT reconstruction + Australarus and Miolarus, new Miocene gulls + avian evolution scientific and artistic representation
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Ben Creisler
Mar 6, 2025, 11:31:15 AM (12 days ago) Mar 6
to DinosaurMa...@googlegroups.com
Ben Creisler
New avian papers:
Jessie Atterholt, Jingmai K. O’Connor & Hailu You (2025)
Osteohistology of Enantiornithine Birds from the Lower Cretaceous Xiagou Formation
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.08.020
https://www.sciencedirect.com/science/article/abs/pii/S001669952500018X
We describe the osteohistology of five enantiornithine bird specimens from Lower Cretaceous Xiagou Formation deposits of the Changma locality in northwestern Gansu Province, China. Samples were taken from the femora of: three specimens of Avimaia schweitzerae (IVPP V25371, IVPP V31956, and GSGM-04-CM-007), Qiliania graffini GSGM-04-CM-006, and Novisavis pubisculata IVPP V31957. The objective of this study is to describe intrageneric variation (in Avimaia), and intertaxonomic variation among enantiornithine birds coexisting in an ecosystem. All five specimens have a femoral cortex composed mainly of parallel fibered bone with relatively low vascularity. All three Avimaia specimens have 2-3 vascular canals, and asymmetrical growth marks, indicating cortical drift. In Qiliania there are eight longitudinal vascular canals, five of which are concentrated in one region of the cortex. Although the gross anatomy of the skeleton and fusion of compound elements indicates morphological maturity, neither growth marks, an outer circumferential layer (OCL), nor an inner circumferential layer (ICL) are present. The femur of Novisavis has some regions of a woven parallel complex and a higher level of vascularity relative to the other specimens (14 longitudinal channels present). Although this specimen is morphologically immature based on gross anatomy, the femur has a well-developed OCL and ICL. These results emphasize the enantiornithine offset between morphological maturity and osteohistological maturity. Development of the OCL appears to be decoupled from morphological maturity, in some cases forming before the skeleton has fully fused, and in others well after. The specimens are similar in size but vary considerably in the number of growth marks present, from none to two. This suggests either developmental plasticity and diverse growth strategies and, complicates attempts to interpret relative age and growth stage in enantiornithines.
The enantiornithine Iberomesornis romerali from the Lower Cretaceous site of Las Hoyas (Spain) was originally described more than 35 years ago. As one of the first known articulated partial skeletons of this clade, I. romerali has been critical to our understanding of early avian systematics. Due to its preservation as a largely two-dimensional slab specimen, previous anatomical descriptions were unable to fully capture its anatomy. Here, we present new anatomical data based on micro-computed tomography of the holotype. We reconstruct five previously poorly known osteological elements, i.e., cervical vertebrae, pygostyle, coracoid, furcula, and humerus. Re-evaluation of these elements resulted in revised scorings for 15 morphological characters commonly used for cladistic analysis of Aves. The results of the modified character matrix support Iberomesornis in a derived position within Enantiornithes, close to the Longipterygidae. In addition, new findings in the coracoid and humerus reveal well-developed muscles for the elevation (i.e., supracoracoideus) and flexion-extension (extensor carpi radiale) of the wing. The new evidences, together with the typical enantiornithine furcula and the small size of the holotype, suggest that I. romerali was capable of flapping flight.
Australarus bakeri gen. et sp. nov.
Miolarus rectirostrum gen. et sp. nov.
Vanesa L. De Pietri, R. Paul Scofield, Suzanne J. Hand, Mike Archer, Alan J.D. Tennyson & Trevor H. Worthy (2025)
Early Miocene gull-like birds (Charadriiformes: Laridae) from New Zealand
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.08.021
https://www.sciencedirect.com/science/article/pii/S0016699525000191
The shorebird family Laridae encompasses gulls, terns, skimmers, and noddies, which today primarily inhabit near-shore marine environments worldwide. Several species of larids of uncertain phylogenetic position within the group have been described from the late Oligocene-Early Miocene of Saint-Gérand-le-Puy, France, but despite this diversity, their global pre-Pliocene fossil record remains poor, especially in the Southern Hemisphere. Here we describe two new species of Laridae from the lacustrine deposits of St Bathans in Central Otago, New Zealand: Australarus bakeri nov. gen., nov. sp., one of the smallest larids known to date, and the medium-sized Miolarus rectirostrum nov. gen., nov. sp. The new species are very distinct from the Oligo-Miocene European taxa, and, at least for A. bakeri, the presence of immature bones indicates local breeding. Australarus bakeri’s distinctiveness and presence of seemingly plesiomorphic features, especially of the humerus and some referred elements may support a phylogenetic position outside crown-group Laridae. The intra-familial relationships of M. rectirostrum remain unclear due to the fragmentary nature of the specimens, despite a resemblance of the maxillary rostrum to some species of gulls. Both new species underscore the diversity and importance of the shorebirds so far described from the Early Miocene St Bathans Fauna.
===
Angela D. Buscalioni (2025)
Scientific and artistic representations in avian evolution
Spanish Journal of Palaeontology (advance online publication)
doi: https://doi.org/10.7203/sjp.30463
https://turia.uv.es/index.php/sjpalaeontology/article/view/30463
Free pdf:
https://turia.uv.es/index.php/sjpalaeontology/article/view/30463/31946
This essay explores the relationship between artistic and scientific perspectives in the depiction of birds' formal organization. It highlights how both fields converge in fundamental questions that shape the identity of avian organisms. Historically, early approaches to avian evolution focused on functional characters, which represented complex adaptations. Birds were later linked to archosaurian reptiles from around 200 million years ago, and their evolution was seen as gradual, emerging from terrestrial organisms. Recent palaeontological discoveries, particularly from the Maniraptora group, have provided well-preserved fossils, supporting the theory that birds are descendants of dinosaurs. These findings suggest that the emergence of birds from their maniraptoriform ancestors occurred in less than 50 million years. Phylogenetic systematics has helped to map out evolutionary transformations based on homologous traits, but discrepancies in these patterns have led to inconsistencies in cladograms. Meanwhile, studies in morphometrics, genetics, and developmental biology have focused on morphological units, interpreting these units through the lens of modularity and evolutionary integration—concepts also explored in art—to understand the new avian Bauplan.
=====
Jessie Atterholt, Jingmai K. O’Connor & Hailu You (2025)
Osteohistology of Enantiornithine Birds from the Lower Cretaceous Xiagou Formation
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.08.020
https://www.sciencedirect.com/science/article/abs/pii/S001669952500018X
We describe the osteohistology of five enantiornithine bird specimens from Lower Cretaceous Xiagou Formation deposits of the Changma locality in northwestern Gansu Province, China. Samples were taken from the femora of: three specimens of Avimaia schweitzerae (IVPP V25371, IVPP V31956, and GSGM-04-CM-007), Qiliania graffini GSGM-04-CM-006, and Novisavis pubisculata IVPP V31957. The objective of this study is to describe intrageneric variation (in Avimaia), and intertaxonomic variation among enantiornithine birds coexisting in an ecosystem. All five specimens have a femoral cortex composed mainly of parallel fibered bone with relatively low vascularity. All three Avimaia specimens have 2-3 vascular canals, and asymmetrical growth marks, indicating cortical drift. In Qiliania there are eight longitudinal vascular canals, five of which are concentrated in one region of the cortex. Although the gross anatomy of the skeleton and fusion of compound elements indicates morphological maturity, neither growth marks, an outer circumferential layer (OCL), nor an inner circumferential layer (ICL) are present. The femur of Novisavis has some regions of a woven parallel complex and a higher level of vascularity relative to the other specimens (14 longitudinal channels present). Although this specimen is morphologically immature based on gross anatomy, the femur has a well-developed OCL and ICL. These results emphasize the enantiornithine offset between morphological maturity and osteohistological maturity. Development of the OCL appears to be decoupled from morphological maturity, in some cases forming before the skeleton has fully fused, and in others well after. The specimens are similar in size but vary considerably in the number of growth marks present, from none to two. This suggests either developmental plasticity and diverse growth strategies and, complicates attempts to interpret relative age and growth stage in enantiornithines.
===
Javier Castro-Terol, Alejandro Pérez-Ramos, Jingmai K. O’Connor, José Luis Sanz & Francisco J. Serrano (2025)
Micro-CT reconstruction reveals new information about the phylogenetic position and locomotion of the Early Cretaceous bird Iberomesornis romerali
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.11.006
https://www.sciencedirect.com/science/article/abs/pii/S001669952500021X
Javier Castro-Terol, Alejandro Pérez-Ramos, Jingmai K. O’Connor, José Luis Sanz & Francisco J. Serrano (2025)
Micro-CT reconstruction reveals new information about the phylogenetic position and locomotion of the Early Cretaceous bird Iberomesornis romerali
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.11.006
https://www.sciencedirect.com/science/article/abs/pii/S001669952500021X
The enantiornithine Iberomesornis romerali from the Lower Cretaceous site of Las Hoyas (Spain) was originally described more than 35 years ago. As one of the first known articulated partial skeletons of this clade, I. romerali has been critical to our understanding of early avian systematics. Due to its preservation as a largely two-dimensional slab specimen, previous anatomical descriptions were unable to fully capture its anatomy. Here, we present new anatomical data based on micro-computed tomography of the holotype. We reconstruct five previously poorly known osteological elements, i.e., cervical vertebrae, pygostyle, coracoid, furcula, and humerus. Re-evaluation of these elements resulted in revised scorings for 15 morphological characters commonly used for cladistic analysis of Aves. The results of the modified character matrix support Iberomesornis in a derived position within Enantiornithes, close to the Longipterygidae. In addition, new findings in the coracoid and humerus reveal well-developed muscles for the elevation (i.e., supracoracoideus) and flexion-extension (extensor carpi radiale) of the wing. The new evidences, together with the typical enantiornithine furcula and the small size of the holotype, suggest that I. romerali was capable of flapping flight.
====
====
Also:
Free pdf:
Australarus bakeri gen. et sp. nov.
Miolarus rectirostrum gen. et sp. nov.
Vanesa L. De Pietri, R. Paul Scofield, Suzanne J. Hand, Mike Archer, Alan J.D. Tennyson & Trevor H. Worthy (2025)
Early Miocene gull-like birds (Charadriiformes: Laridae) from New Zealand
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.08.021
https://www.sciencedirect.com/science/article/pii/S0016699525000191
The shorebird family Laridae encompasses gulls, terns, skimmers, and noddies, which today primarily inhabit near-shore marine environments worldwide. Several species of larids of uncertain phylogenetic position within the group have been described from the late Oligocene-Early Miocene of Saint-Gérand-le-Puy, France, but despite this diversity, their global pre-Pliocene fossil record remains poor, especially in the Southern Hemisphere. Here we describe two new species of Laridae from the lacustrine deposits of St Bathans in Central Otago, New Zealand: Australarus bakeri nov. gen., nov. sp., one of the smallest larids known to date, and the medium-sized Miolarus rectirostrum nov. gen., nov. sp. The new species are very distinct from the Oligo-Miocene European taxa, and, at least for A. bakeri, the presence of immature bones indicates local breeding. Australarus bakeri’s distinctiveness and presence of seemingly plesiomorphic features, especially of the humerus and some referred elements may support a phylogenetic position outside crown-group Laridae. The intra-familial relationships of M. rectirostrum remain unclear due to the fragmentary nature of the specimens, despite a resemblance of the maxillary rostrum to some species of gulls. Both new species underscore the diversity and importance of the shorebirds so far described from the Early Miocene St Bathans Fauna.
===
Free pdf:
Angela D. Buscalioni (2025)
Scientific and artistic representations in avian evolution
Spanish Journal of Palaeontology (advance online publication)
doi: https://doi.org/10.7203/sjp.30463
https://turia.uv.es/index.php/sjpalaeontology/article/view/30463
Free pdf:
https://turia.uv.es/index.php/sjpalaeontology/article/view/30463/31946
This essay explores the relationship between artistic and scientific perspectives in the depiction of birds' formal organization. It highlights how both fields converge in fundamental questions that shape the identity of avian organisms. Historically, early approaches to avian evolution focused on functional characters, which represented complex adaptations. Birds were later linked to archosaurian reptiles from around 200 million years ago, and their evolution was seen as gradual, emerging from terrestrial organisms. Recent palaeontological discoveries, particularly from the Maniraptora group, have provided well-preserved fossils, supporting the theory that birds are descendants of dinosaurs. These findings suggest that the emergence of birds from their maniraptoriform ancestors occurred in less than 50 million years. Phylogenetic systematics has helped to map out evolutionary transformations based on homologous traits, but discrepancies in these patterns have led to inconsistencies in cladograms. Meanwhile, studies in morphometrics, genetics, and developmental biology have focused on morphological units, interpreting these units through the lens of modularity and evolutionary integration—concepts also explored in art—to understand the new avian Bauplan.
Ben Creisler
Mar 9, 2025, 10:56:24 PM (9 days ago) Mar 9
to DinosaurMa...@googlegroups.com
The first paper is now free:
Jessie Atterholt, Jingmai K. O’Connor & Hailu You (2025)
Osteohistology of Enantiornithine Birds from the Lower Cretaceous Xiagou Formation
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.08.020
https://www.sciencedirect.com/science/article/abs/pii/S001669952500018X
Osteohistology of Enantiornithine Birds from the Lower Cretaceous Xiagou Formation
Geobios (advance online publication)
doi: https://doi.org/10.1016/j.geobios.2024.08.020
https://www.sciencedirect.com/science/article/abs/pii/S001669952500018X
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