Manidens postcranial osteology + Triceratops cranial ornamentation
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Ben Creisler
Dec 19, 2025, 12:00:39 PM12/19/25
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Ben Creisler
New papers:
Ceratopsids are among the most distinctive and well known extinct Cretaceous vertebrates, yet many details regarding the growth and composition of their cranial features are still not fully anatomically described or understood. In particular, striking cranial adornments such as the postorbital horns and parietal-squamosal frill of Triceratops experience a series of major morphological and histological shifts throughout ontogeny. While previous osteohistological studies have largely focused on the parietal of Triceratops, there are relatively few studies of postorbital horn and squamosal histology. Here we present an in-depth osteohistological description of the postorbital horns and squamosal from a single subadult Triceratops horridus specimen and compare similar histological features among ceratopsian cranial ornaments. Analysis revealed the postorbital horns display considerable histological variation based on sampling location, with our proximal section describing an extensive range of vascularity across three notable horizons previously undocumented, suggesting that histological ontogenetic assessments could differ across ornamental structures. Although the Triceratops squamosal maintains similarities with remodeled bone among other ceratopsid parietals, distinct growth marks are preserved near the periosteal surface containing at least three lines of arrested growth, citing a novel developmental shift from rapid azonal to slowed zonal growth late in ontogeny. Additionally, although some metrics of cranial size remain relatively unreliable characteristics for assessing ontogeny, occipital condyle dimensions may offer an avenue of delineating ontogenetically older Triceratops individuals. Alongside morphological measurements, extensive histological sampling may provide a means to clarify currently perceived anatomical inconsistencies and heterochronic variation between putative adults and subadults of Triceratops and other ceratopsids.
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Marcos G. Becerra, Diego Pol, Ignacio A. Cerda, Laura B. Porro & Oliver W. M. Rauhut (2025)
Postcranial osteology of Manidens condorensis (Ornithischia: Heterodontosauridae) from the Lower Jurassic of Argentina: 3D reconstruction, histology, and phylogenetic implications
Papers in Palaeontology 11(6): e70053
doi: https://doi.org/10.1002/spp2.70053
https://onlinelibrary.wiley.com/doi/epdf/10.1002/spp2.70053
Postcranial osteology of Manidens condorensis (Ornithischia: Heterodontosauridae) from the Lower Jurassic of Argentina: 3D reconstruction, histology, and phylogenetic implications
Papers in Palaeontology 11(6): e70053
doi: https://doi.org/10.1002/spp2.70053
https://onlinelibrary.wiley.com/doi/epdf/10.1002/spp2.70053
Manidens condorensis, a small-bodied heterodontosaurid from the Lower Jurassic Cañadón Asfalto Formation of Patagonia, represents the most complete ornithischian dinosaur currently known from South America for this interval. This study presents the first detailed description of its postcranial skeleton, based on high-resolution micro-computed tomography and 3D reconstructions of the holotype specimen (MPEF-PV 3211). We describe the first recorded proatlas in a heterodontosaurid, together with the description of vertebrae from all regions, pectoral and pelvic girdles, and preserved ribs and tendons, which offer new comparative insights into early ornithischians. Histological sections from thoracic ribs indicate a subadult ontogenetic stage and provide information on growth dynamics and tissue structure. Taphonomic analysis of the holotype, informed by disarticulation patterns and bone orientations, indicates low-energy depositional conditions and a left-side-down post-mortem resting position. Updated anatomical data were incorporated into both comprehensive and targeted phylogenetic analyses, with an emphasis on heterodontosaurid relationships. Results support the placement of Manidens as a transitional form between more basal Laurasian and more derived Gondwanan heterodontosaurids, combining plesiomorphic and specialized features, identify novel postcranial autapomorphies for Manidens, and highlight increased similarities with more complete taxa. These findings strengthen its role as a key taxon for understanding early ornithischian diversification and the evolution of herbivorous adaptations. The integration of osteology, taphonomy, histology and phylogenetics in this study significantly expands our knowledge of Manidens and its evolutionary context within Heterodontosauridae.
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Free pdf:
Kyle D. Obuszewski, N. Adam Smith & Guinevere Rose Brown (2025)
An osteohistological analysis of Triceratops (Ornithischia: Ceratopsidae) cranial ornamentation
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70117
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70117
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.70117
Kyle D. Obuszewski, N. Adam Smith & Guinevere Rose Brown (2025)
An osteohistological analysis of Triceratops (Ornithischia: Ceratopsidae) cranial ornamentation
The Anatomical Record (advance online publication)
doi: https://doi.org/10.1002/ar.70117
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.70117
Free pdf:
https://anatomypubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ar.70117
Ceratopsids are among the most distinctive and well known extinct Cretaceous vertebrates, yet many details regarding the growth and composition of their cranial features are still not fully anatomically described or understood. In particular, striking cranial adornments such as the postorbital horns and parietal-squamosal frill of Triceratops experience a series of major morphological and histological shifts throughout ontogeny. While previous osteohistological studies have largely focused on the parietal of Triceratops, there are relatively few studies of postorbital horn and squamosal histology. Here we present an in-depth osteohistological description of the postorbital horns and squamosal from a single subadult Triceratops horridus specimen and compare similar histological features among ceratopsian cranial ornaments. Analysis revealed the postorbital horns display considerable histological variation based on sampling location, with our proximal section describing an extensive range of vascularity across three notable horizons previously undocumented, suggesting that histological ontogenetic assessments could differ across ornamental structures. Although the Triceratops squamosal maintains similarities with remodeled bone among other ceratopsid parietals, distinct growth marks are preserved near the periosteal surface containing at least three lines of arrested growth, citing a novel developmental shift from rapid azonal to slowed zonal growth late in ontogeny. Additionally, although some metrics of cranial size remain relatively unreliable characteristics for assessing ontogeny, occipital condyle dimensions may offer an avenue of delineating ontogenetically older Triceratops individuals. Alongside morphological measurements, extensive histological sampling may provide a means to clarify currently perceived anatomical inconsistencies and heterochronic variation between putative adults and subadults of Triceratops and other ceratopsids.
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