Platypterygius elsuntuoso, new ichthyosaur species from Colombia + Globidens jaws from Texas + reptile ear ossicle origin (free pdfs)
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Ben Creisler
Sep 21, 2024, 2:15:17 PMSep 21
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Ben Creisler
Recent reptile papers:
María Eurídice Páramo Fonseca, Cristian David Benavides Cabra & Renzo Garavito Camacho (2024)
A new species of Platypterygius (Ophthalmosauridae) from the lower Barremian of Colombia and assessment of the species composition of the genus
Una nueva especie de Platypterygius (Ophthalmosauridae) del Barremiano inferior de Colombia y evaluación de la composición específica del género
Earth Sciences Research Journal 28(2): 103–126
DOI: https://doi.org/10.15446/esrj.v28n2.112332
https://revistas.unal.edu.co/index.php/esrj/article/view/112332
Free pdf:
https://revistas.unal.edu.co/index.php/esrj/article/view/112332/93137
In this paper, we describe a new ophthalmosaurid specimen found in the lower Barremian beds of the Paja Formation at Villa de Leiva, Boyacá, Colombia. The specimen represents a new species of Platypterygius, P. elsuntuoso sp. nov. defined by three unique features within the genus: a small ventral peg in the anterior ventral border of the extracondylar area of the basioccipital; a supratemporal groove in the quadrate; and a shallow neck at the base of the acellular cementum ring on the teeth root. In support of our taxonomic determination, in this contribution we also assess the species composition of the genus Platypterygius, comparing the known anatomy of the type species P. platydactylus with that of the other species pre-viously assigned to the genus. We found that a great morphological affinity in the forelimb of the species P. americanus, P. australis, P. hercynicus, and P. sachicarum (lower Barremian to lower Cenomanian) with that of the type species (Aptian) is unquestionable and differentiate them from all other ophthalmosaurids. Three new diagnostic features (synapomorphies of the genus) support their inclusion in Platypterygius. Consequently, the genus name “Kyhytysuka”, recently proposed to differentiate P. sachicarum from the genus Platypterygius is here rejected. A careful comparison of the cranial characteris-tics of Platypterygius specimens preserving associated cranial and fin remains demonstrate that Platypterygius is a genus distinguishable from other ophthalmosaurids not only by a typical forelimb but also by a particular combination of skull features. In this context, the skull morphology of “Simbirskiasaurus” concurs with that defining Platypterygius and its mi-nor differences are not sufficient to support its generic distinction. The morphological comparisons and our phylogenetic analysis show the new species P. elsuntuoso more closely related to the Colombian species P. sachicarum than to other species of Platypterygius. Given that the new species came from the lower Barremian and P. sachicarum came from the upper Barremian, the minor differences in dentition found between the two species suggest a speciation by adaptation to new food sources in the Cretaceous epicontinental sea of Colombia.
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Trevor H. Rempert, Brennan P. Martens, Alexander P. M. Vinkeles Melchers & Ashley N. Rempert (2024)
New remains of the mosasaur Globidens alabamaensis from the North Sulphur River of Texas
The Journal of Paleontological Sciences: JPS.C.24.0001
https://www.researchgate.net/publication/383117647_New_remains_of_the_mosasaur_Globidens_alabamaensis_from_the_North_Sulphur_River_of_Texas
https://zenodo.org/records/13324299
Here, we report on the important discovery of two well-preserved maxillae from the durophagous mosasaur Globidens alabamaensis Gilmore, 1912. The maxillae were found in the Ozan Formation embedded in the North Sulphur River channel near Ladonia, Fannin County, Texas, USA. Both maxillae preserve nearly complete tooth rows. In North America, Globidens is amongst the rarest mosasaurs, with remains consisting predominantly of isolated teeth and jaw fragments.
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New remains of the mosasaur Globidens alabamaensis from the North Sulphur River of Texas
Free pdf:
Ingmar Werneburg & Mario Bronzati (2024)
Trifold origin of the reptilian ear ossicle and its relation to the evolutionary modification of the temporal skull region
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.14105
https://onlinelibrary.wiley.com/doi/10.1111/joa.14105
Whereas mammals are characterized by the presence of three middle ear ossicles, reptiles have only one, the columella (stapes). Nevertheless, there is a great diversity of columellar anatomy among sauropsids, especially in the unique and cartilaginous “extracolumella”-portion. Molecular studies revealed the “columella” of chicken and quails to be formed within the second pharyngeal arch, although conflicting evidence exists for the columellar footplate and distal parts of the columella in these birds. We studied columellar development in four turtles, one lizard, and one caiman species and argue, using early blastematous stages, that, distally, the so-called “extracolumella” in turtles is mainly of quadrate, that is, first pharyngeal arch origin. Differently, the dorsal aspect of the “extracolumella” of the lizard and a part of the “dorsal columella process” of the caiman are likely quadrate-derived. This indicates only a partial homology of the distal columellar compartments among reptiles. Moreover, we observed in most species that, at early stages, the footplate differentiates from the otic capsule, which confirms widespread experimental findings of mesodermal cells contributing to the proximal part of the columella. We provide a hypothetical framework for the changes in the columella and quadrate morphology in reptilian evolution. Originally, as evidenced by the fossil record, the columella served as a stabilizing brace between the quadrate and braincase. Associated with changes in the feeding mode of late Permian taxa, the quadrate was integrated along the stress flows from biting, and in early development part of the quadrate differentiated to differently contribute to the distal part of the “columella-complex,” which now contacts the tympanic membrane. In addition, part of the original otic capsule contributes to the footplate of the mobile columella, providing a connection with the inner ear.
=======
Free pdf:
Platypterygius elsuntuoso sp. nov.
Platypterygius elsuntuoso sp. nov.
María Eurídice Páramo Fonseca, Cristian David Benavides Cabra & Renzo Garavito Camacho (2024)
A new species of Platypterygius (Ophthalmosauridae) from the lower Barremian of Colombia and assessment of the species composition of the genus
Una nueva especie de Platypterygius (Ophthalmosauridae) del Barremiano inferior de Colombia y evaluación de la composición específica del género
Earth Sciences Research Journal 28(2): 103–126
DOI: https://doi.org/10.15446/esrj.v28n2.112332
https://revistas.unal.edu.co/index.php/esrj/article/view/112332
Free pdf:
https://revistas.unal.edu.co/index.php/esrj/article/view/112332/93137
In this paper, we describe a new ophthalmosaurid specimen found in the lower Barremian beds of the Paja Formation at Villa de Leiva, Boyacá, Colombia. The specimen represents a new species of Platypterygius, P. elsuntuoso sp. nov. defined by three unique features within the genus: a small ventral peg in the anterior ventral border of the extracondylar area of the basioccipital; a supratemporal groove in the quadrate; and a shallow neck at the base of the acellular cementum ring on the teeth root. In support of our taxonomic determination, in this contribution we also assess the species composition of the genus Platypterygius, comparing the known anatomy of the type species P. platydactylus with that of the other species pre-viously assigned to the genus. We found that a great morphological affinity in the forelimb of the species P. americanus, P. australis, P. hercynicus, and P. sachicarum (lower Barremian to lower Cenomanian) with that of the type species (Aptian) is unquestionable and differentiate them from all other ophthalmosaurids. Three new diagnostic features (synapomorphies of the genus) support their inclusion in Platypterygius. Consequently, the genus name “Kyhytysuka”, recently proposed to differentiate P. sachicarum from the genus Platypterygius is here rejected. A careful comparison of the cranial characteris-tics of Platypterygius specimens preserving associated cranial and fin remains demonstrate that Platypterygius is a genus distinguishable from other ophthalmosaurids not only by a typical forelimb but also by a particular combination of skull features. In this context, the skull morphology of “Simbirskiasaurus” concurs with that defining Platypterygius and its mi-nor differences are not sufficient to support its generic distinction. The morphological comparisons and our phylogenetic analysis show the new species P. elsuntuoso more closely related to the Colombian species P. sachicarum than to other species of Platypterygius. Given that the new species came from the lower Barremian and P. sachicarum came from the upper Barremian, the minor differences in dentition found between the two species suggest a speciation by adaptation to new food sources in the Cretaceous epicontinental sea of Colombia.
========
Free pdf:
Trevor H. Rempert, Brennan P. Martens, Alexander P. M. Vinkeles Melchers & Ashley N. Rempert (2024)
New remains of the mosasaur Globidens alabamaensis from the North Sulphur River of Texas
The Journal of Paleontological Sciences: JPS.C.24.0001
https://www.researchgate.net/publication/383117647_New_remains_of_the_mosasaur_Globidens_alabamaensis_from_the_North_Sulphur_River_of_Texas
https://zenodo.org/records/13324299
Here, we report on the important discovery of two well-preserved maxillae from the durophagous mosasaur Globidens alabamaensis Gilmore, 1912. The maxillae were found in the Ozan Formation embedded in the North Sulphur River channel near Ladonia, Fannin County, Texas, USA. Both maxillae preserve nearly complete tooth rows. In North America, Globidens is amongst the rarest mosasaurs, with remains consisting predominantly of isolated teeth and jaw fragments.
****
New remains of the mosasaur Globidens alabamaensis from the North Sulphur River of Texas
Free pdf:
Ingmar Werneburg & Mario Bronzati (2024)
Trifold origin of the reptilian ear ossicle and its relation to the evolutionary modification of the temporal skull region
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.14105
https://onlinelibrary.wiley.com/doi/10.1111/joa.14105
Whereas mammals are characterized by the presence of three middle ear ossicles, reptiles have only one, the columella (stapes). Nevertheless, there is a great diversity of columellar anatomy among sauropsids, especially in the unique and cartilaginous “extracolumella”-portion. Molecular studies revealed the “columella” of chicken and quails to be formed within the second pharyngeal arch, although conflicting evidence exists for the columellar footplate and distal parts of the columella in these birds. We studied columellar development in four turtles, one lizard, and one caiman species and argue, using early blastematous stages, that, distally, the so-called “extracolumella” in turtles is mainly of quadrate, that is, first pharyngeal arch origin. Differently, the dorsal aspect of the “extracolumella” of the lizard and a part of the “dorsal columella process” of the caiman are likely quadrate-derived. This indicates only a partial homology of the distal columellar compartments among reptiles. Moreover, we observed in most species that, at early stages, the footplate differentiates from the otic capsule, which confirms widespread experimental findings of mesodermal cells contributing to the proximal part of the columella. We provide a hypothetical framework for the changes in the columella and quadrate morphology in reptilian evolution. Originally, as evidenced by the fossil record, the columella served as a stabilizing brace between the quadrate and braincase. Associated with changes in the feeding mode of late Permian taxa, the quadrate was integrated along the stress flows from biting, and in early development part of the quadrate differentiated to differently contribute to the distal part of the “columella-complex,” which now contacts the tympanic membrane. In addition, part of the original otic capsule contributes to the footplate of the mobile columella, providing a connection with the inner ear.
=======
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