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Chatar N, Boman R, Fischer V, Segura V, Julémont C, Tseng ZJ. Growing sabers: Mandibular shape and biomechanical performance trajectories during the ontogeny of Smilodon fatalis. Anat Rec (Hoboken) 2024. [PMID: 38801020 DOI: 10.1002/ar.25504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/28/2024] [Accepted: 05/02/2024] [Indexed: 05/29/2024]
Abstract
The evolution of organisms can be studied through the lens of developmental systems, as the timing of development of morphological features is an important aspect to consider when studying a phenotype. Such data can be challenging to obtain in fossil amniotes owing to the scarcity of their fossil record. However, the numerous remains of Rancho La Brea allow a detailed study of the postnatal changes in an extinct sabertoothed felid: Smilodon fatalis. Despite numerous previous studies on the ontogeny of Smilodon, an important question remained open: how did the cubs of Smilodon acquire and process food? By applying 3D geometric morphometrics and finite element analyses to 49 mandibles at various developmental stages (22 of S. fatalis, 23 of Panthera leo, and 4 of early diverging felids), we assess the changes in mandibular shape and performance during growth. Both lions and sabertooths exhibit a shift in mandibular shape, aligning with eruption of the lower carnassial. This marks the end of weaning in lions and suggests a prolonged weaning period in S. fatalis owing to its delayed eruption sequence. We also highlight distinct ontogenetic trajectories, with S. fatalis undergoing more postnatal mandibular shape changes. Finally, although S. fatalis appears more efficient than P. leo at performing an anchor bite, this efficiency is acquired through ontogeny and at a quite late age. The delayed shape change compared with P. leo and the low biting efficiency during the growth in Smilodon could indicate an extended duration of the parental care compared with P. leo.
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Affiliation(s)
- Narimane Chatar
- Evolution and Diversity Dynamics Lab, UR Geology, Université de Liège, Liège, Belgium
- Functional Anatomy and Vertebrate Evolution Lab, Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Romain Boman
- Department of Aerospace and Mechanical Engineering, Non-Linear Computational Mechanics (MN2L) Research Group, Université de Liège, Liège, Belgium
| | - Valentin Fischer
- Evolution and Diversity Dynamics Lab, UR Geology, Université de Liège, Liège, Belgium
| | - Valentina Segura
- Unidad Ejecutora Lillo, Consejo Nacional de Investigaciones Científicas y Técnicas (conicet)-Fundación Miguel Lillo, San Miguel de Tucumán, Argentina
| | - Cara Julémont
- Evolution and Diversity Dynamics Lab, UR Geology, Université de Liège, Liège, Belgium
| | - Z Jack Tseng
- Functional Anatomy and Vertebrate Evolution Lab, Department of Integrative Biology, University of California, Berkeley, California, USA
- University of California Museum of Paleontology, Department of Integrative Biology, University of California, Berkeley, California, USA
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Mychajliw AM, Rice KA, Tewksbury LR, Southon JR, Lindsey EL. Exceptionally preserved asphaltic coprolites expand the spatiotemporal range of a North American paleoecological proxy. Sci Rep 2020; 10:5069. [PMID: 32193515 PMCID: PMC7081288 DOI: 10.1038/s41598-020-61996-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 03/07/2020] [Indexed: 11/09/2022] Open
Abstract
As fossilized feces, coprolites represent direct evidence of animal behavior captured in the fossil record. They encapsulate past ecological interactions between a consumer and its prey and, when they contain plant material, can also guide paleoenvironmental reconstructions. Here we describe the first coprolites from the lagerstätte Rancho La Brea (RLB) in Los Angeles, California, which also represent the first confirmed coprolites from an asphaltic (“tar pit”) context globally. Combining multiple lines of evidence, including radiocarbon dating, body size reconstructions, stable isotope analysis, scanning electron microscopy, and sediment analyses, we document hundreds of rodent coprolites found in association with plant material, and tentatively assign them to the woodrat genus Neotoma. Neotoma nests (i.e., middens) and their associated coprolites inform paleoclimatic reconstructions for the arid southwestern US but are not typically preserved in coastal areas due to environmental and physiological characteristics. The serendipitous activity of an asphalt seep preserved coprolites and their original cellulosic material for 50,000 years at RLB, yielding a snapshot of coastal California during Marine Isotope Stage 3. This discovery augments the proxies available at an already critical fossil locality and highlights the potential for more comprehensive paleoenvironmental analyses at other asphaltic localities globally.
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Affiliation(s)
- Alexis M Mychajliw
- La Brea Tar Pits & Museum, 5801 Wilshire Blvd, Los Angeles, California, 90036, USA. .,Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan. .,Laboratories of Molecular Anthropology and Microbiome Research, University of Oklahoma, Norman, OK, 73019, USA.
| | - Karin A Rice
- La Brea Tar Pits & Museum, 5801 Wilshire Blvd, Los Angeles, California, 90036, USA
| | - Laura R Tewksbury
- La Brea Tar Pits & Museum, 5801 Wilshire Blvd, Los Angeles, California, 90036, USA
| | - John R Southon
- Department of Earth System Science, UC Irvine, Keck CCAMS Group, Irvine, California, 92697, USA
| | - Emily L Lindsey
- La Brea Tar Pits & Museum, 5801 Wilshire Blvd, Los Angeles, California, 90036, USA
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Brannick AL, Wilson GP. New Specimens of the Late Cretaceous Metatherian Eodelphis and the Evolution of Hard-Object Feeding in the Stagodontidae. J MAMM EVOL 2018. [DOI: 10.1007/s10914-018-9451-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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