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Mosasaurus from Upper Cretaceous in Bulgaria + Marine vertebrates from Cretaceous Hartland Shale of Kansas + caiman life history + Komodo dragon skull + more
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Ben Creisler
Dec 24, 2024, 3:18:38 PM12/24/24
to DinosaurMa...@googlegroups.com
Ben Creisler
Not yet mentioned or not yet fully posted reptile papers:
Docho Dochev, Lubomir Metodiev & Georgi Granchovski (2024)
A new record of Mosasaurus from the Upper Cretaceous in Bulgaria
Review of the Bulgarian Geological Society 85(3): 58-61
doi: https://doi.org/10.52215/rev.bgs.2024.85.3.58
https://bgd.bg/REVIEW_BGS/REVIEW_BGD_2024_3/PDF/13_Dochev_REV_BGS_2024-3.pdf
We report a new mosasaur material from the Upper Cretaceous strata of the Central Balkan Mts. (Bulgaria), comprising several mandibular and/or dentary? that are briefly described and pictured. The final preparation is going to take more time, but the findings are worth recording at this moment. Considering the tooth crown morphology, we assume that the fossils belong to the genus Mosasaurus. These remains originate from levels yielding the inoceramid species Endocostea typica, which dates them as early Maastrichtian. In Bulgaria, this is the oldest known mosasaur record to date.
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Brianna E. Ortiz and Kenshu Shimada (2024)
Fossil Marine Vertebrates from the Upper Part of the Upper Cretaceous Hartland Shale from Republic County, Kansas, USA.
Transactions of the Kansas Academy of Science 127(3-4): 135-144
doi: https://doi.org/10.1660/062.127.0308
https://bioone.org/journals/transactions-of-the-kansas-academy-of-science/volume-127/issue-3-4/062.127.0308/Fossil-Marine-Vertebrates-from-the-Upper-Part-of-the-Upper/10.1660/062.127.0308.short
The Hartland Shale of the Greenhorn Limestone is a geologic unit broadly distributed in north-central Kansas, that formed in the Western Interior Seaway, a Late Cretaceous epicontinental seaway in North America. Previously, the vertebrate fossil record of the Hartland Shale of Kansas was confined only to a tooth of the extinct lamniform shark Cretoxyrhina mantelli and skeletal remains of a plesiosaur, besides taxonomically uninformative bones and teeth of bony fishes. In this study, we describe 18 vertebrate taxa from the Hartland Shale in Republic County, Kansas, comprising five chondrichthyans (including C. mantelli), 12 osteichthyan fishes, and one reptilian taxon. These newly collected materials, which are dated approximately 93.95 million years ago around the Cenomanian-Turonian transition, provide new insights into the marine ecosystem and environmental conditions during the deposition of the Hartland Shale in Kansas.
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Fossil Marine Vertebrates from the Upper Part of the Upper Cretaceous Hartland Shale from Republic County, Kansas, USA.
Transactions of the Kansas Academy of Science 127(3-4): 135-144
doi: https://doi.org/10.1660/062.127.0308
https://bioone.org/journals/transactions-of-the-kansas-academy-of-science/volume-127/issue-3-4/062.127.0308/Fossil-Marine-Vertebrates-from-the-Upper-Part-of-the-Upper/10.1660/062.127.0308.short
The Hartland Shale of the Greenhorn Limestone is a geologic unit broadly distributed in north-central Kansas, that formed in the Western Interior Seaway, a Late Cretaceous epicontinental seaway in North America. Previously, the vertebrate fossil record of the Hartland Shale of Kansas was confined only to a tooth of the extinct lamniform shark Cretoxyrhina mantelli and skeletal remains of a plesiosaur, besides taxonomically uninformative bones and teeth of bony fishes. In this study, we describe 18 vertebrate taxa from the Hartland Shale in Republic County, Kansas, comprising five chondrichthyans (including C. mantelli), 12 osteichthyan fishes, and one reptilian taxon. These newly collected materials, which are dated approximately 93.95 million years ago around the Cenomanian-Turonian transition, provide new insights into the marine ecosystem and environmental conditions during the deposition of the Hartland Shale in Kansas.
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Yohan Pochat-Cottilloux, Gwendal Perrichon, Lionel Hautier, Nicolas Rinder, Romain Amiot, Irena Raselli, Jérôme Adrien, Joël Lachambre, Vincent Fernandez & Jeremy E. Martin (2024)
Size, not phylogeny, explains the morphology of the endosseous labyrinth in the crown clade Crocodylia
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.14170
https://onlinelibrary.wiley.com/doi/10.1111/joa.14170
The endosseous labyrinths are associated with several functions, including hearing and spatial orientation. Throughout their evolutionary history, crocodylomorphs have thrived in diverse environments, and the morphology of their endosseous labyrinths has been suggested as a proxy for inferring their lifestyle. However, the relationships between the shape of their endosseous labyrinths and ontogenetic and phylogenetic factors are difficult to interpret and have rarely been investigated in depth previously, particularly in terms of dataset size. Here, we present the most complete dataset to date on the endosseous labyrinths of extant crocodylians, including 111 specimens covering 22 species of different ontogenetic status (from hatchlings to adults). Using 3D geometric morphometrics, we show that allometry constitutes a major contributor of the shape variation of the crocodylian endosseous labyrinths and that the development of this structure is likely linked to the braincase conformation, in all extant genera. We also find a moderate phylogenetic signal, but only without considering the size effect, so it could not be translated into relevant discrete morphological characters. Based on these results, we discuss several remaining problems that prevent the inclusion of fossil forms with highly divergent lifestyles to study how ecological differences shaped the endosseous labyrinths of crocodylomorphs.
Size, not phylogeny, explains the morphology of the endosseous labyrinth in the crown clade Crocodylia
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.14170
https://onlinelibrary.wiley.com/doi/10.1111/joa.14170
The endosseous labyrinths are associated with several functions, including hearing and spatial orientation. Throughout their evolutionary history, crocodylomorphs have thrived in diverse environments, and the morphology of their endosseous labyrinths has been suggested as a proxy for inferring their lifestyle. However, the relationships between the shape of their endosseous labyrinths and ontogenetic and phylogenetic factors are difficult to interpret and have rarely been investigated in depth previously, particularly in terms of dataset size. Here, we present the most complete dataset to date on the endosseous labyrinths of extant crocodylians, including 111 specimens covering 22 species of different ontogenetic status (from hatchlings to adults). Using 3D geometric morphometrics, we show that allometry constitutes a major contributor of the shape variation of the crocodylian endosseous labyrinths and that the development of this structure is likely linked to the braincase conformation, in all extant genera. We also find a moderate phylogenetic signal, but only without considering the size effect, so it could not be translated into relevant discrete morphological characters. Based on these results, we discuss several remaining problems that prevent the inclusion of fossil forms with highly divergent lifestyles to study how ecological differences shaped the endosseous labyrinths of crocodylomorphs.
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Free pdf:
Pereyra Maria Eugenia, Paula Bona, Pablo Siroski & Anusuya Chinsamy (2025)
Analyzing the Life History of Caimans: The Growth Dynamics of Caiman latirostris From an Osteohistological Approach
Journal of Morphology 286(1): e70010
doi: https://doi.org/10.1002/jmor.70010
https://onlinelibrary.wiley.com/doi/10.1002/jmor.70010
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.70010
Skeletochronology and growth dynamics are intensively investigated in vertebrate osteohistology. These techniques are particularly important for interpreting the life history of long-lived species, such as crocodilians. To understand the longevity, growth dynamics, sexual maturity, and sexual dimorphism of caimans we studied an almost complete ontogenetic series of captive and wild specimens of Caiman latirostris from different localities of Argentina. We identified both cyclical and noncyclical growth marks in juvenile caimans, and we suggest that the latter are associated with environmental stress. By overlapping the growth marks of different individuals, we were able to estimate the minimum age of each specimen. Variations in growth rate are evident in different bones, with the femur and scapula having the highest growth rates, while the fibula and pubis have much slower growth rates. We were able to determine the approximate age of sexual maturity from growth curves deduced from osteohistology, which concurred with those assessed in ecological studies. Additionally based on the growth curves we were able to document different growth dynamics which may be related to sexual dimorphism. This study provides valuable insights into the life history and ecological dynamics of crocodilians, shedding light on their growth patterns, attainment of sexual maturity, and the influence of environmental factors on growth. Furthermore it documents the intraspecific and interelemental osteohistological variation in crocodilians and has direct implications for studies that assess the life history of extinct archosaurs and other sauropsids.
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Free pdf:
Momoko Kubota, Jakob Hallermann, André Beerlink & Alexander Haas (2024)
The skull morphology of the Komodo dragon, Varanus komodoensis (Reptilia, Squamata, Varanidae) — a digital-dissection study
Evolutionary Systematics 8(2): 219-245
doi: https://doi.org/10.3897/evolsyst.8.121149
https://evolsyst.pensoft.net/article/121149/
This study reports the cranial skeletal morphology of Varanus komodoensis Ouwens, 1912. Employing a high-resolution CT scan with subsequent use of 3D data visualization and analysis software, we generated a comprehensive 3D representation of the skull. Reconstruction of the osteoderm and 30 paired and unpaired bones was undertaken, and a detailed examination, comparison, and discussion of these structures were conducted in the context of existing literature. Special attention was given to morphological adaptations and phylogenetic relationships.
The cranial morphology of V. komodoensis exhibits a pronounced adaptation to feeding behavior, characterized by a highly fenestrated skull and sharp ziphodont teeth, presumably optimized for the species’ distinctive hold-and-pull feeding technique.
Several anatomical indicators of cranial kinesis were identified in the skull of V. komodoensis. The absence of the lower temporal bar is linked to the evolution of streptostyly, enabling the free oscillation of the quadrate. The lack of an osteoderm at the frontoparietal suture and the disruption of the postorbital bar provide evidence of mesokinesis. Additionally, loose connections in various cranial segments and the long mandible were interpreted as mobile connections, possibly facilitating the adaptation for swallowing large prey objects.
A review of character states from existing literature reveals synapomorphies between the skull of Varanus komodoensis and the extinct V. priscus (Megalania) Owen, 1859, and also complemented the autapomorphic character states characteristic of the genus Varanus.
The skull morphology of the Komodo dragon, Varanus komodoensis (Reptilia, Squamata, Varanidae) — a digital-dissection study
Evolutionary Systematics 8(2): 219-245
doi: https://doi.org/10.3897/evolsyst.8.121149
https://evolsyst.pensoft.net/article/121149/
This study reports the cranial skeletal morphology of Varanus komodoensis Ouwens, 1912. Employing a high-resolution CT scan with subsequent use of 3D data visualization and analysis software, we generated a comprehensive 3D representation of the skull. Reconstruction of the osteoderm and 30 paired and unpaired bones was undertaken, and a detailed examination, comparison, and discussion of these structures were conducted in the context of existing literature. Special attention was given to morphological adaptations and phylogenetic relationships.
The cranial morphology of V. komodoensis exhibits a pronounced adaptation to feeding behavior, characterized by a highly fenestrated skull and sharp ziphodont teeth, presumably optimized for the species’ distinctive hold-and-pull feeding technique.
Several anatomical indicators of cranial kinesis were identified in the skull of V. komodoensis. The absence of the lower temporal bar is linked to the evolution of streptostyly, enabling the free oscillation of the quadrate. The lack of an osteoderm at the frontoparietal suture and the disruption of the postorbital bar provide evidence of mesokinesis. Additionally, loose connections in various cranial segments and the long mandible were interpreted as mobile connections, possibly facilitating the adaptation for swallowing large prey objects.
A review of character states from existing literature reveals synapomorphies between the skull of Varanus komodoensis and the extinct V. priscus (Megalania) Owen, 1859, and also complemented the autapomorphic character states characteristic of the genus Varanus.
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