1
|
Bennion RF, Maxwell EE, Lambert O, Fischer V. Craniodental ecomorphology of the large Jurassic ichthyosaurian Temnodontosaurus. J Anat 2024; 244:22-41. [PMID: 37591692 PMCID: PMC10734653 DOI: 10.1111/joa.13939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 08/19/2023] Open
Abstract
Marine amniotes have played many crucial roles in ocean ecosystems since the Triassic, including predation at the highest trophic levels. One genus often placed into this guild is the large Early Jurassic neoichthyosaurian Temnodontosaurus, the only post-Triassic ichthyosaurian known with teeth which bear a distinct cutting edge or carina. This taxonomically problematic genus is currently composed of seven species which show a wide variety of skull and tooth morphologies. Here we assess the craniodental disparity in Temnodontosaurus using a series of functionally informative traits. We describe the range of tooth morphologies in the genus in detail, including the first examples of serrated carinae in ichthyosaurians. These consist of false denticles created by the interaction of enamel ridgelets with the carinal keel, as well as possible cryptic true denticles only visible using scanning electron microscopy. We also find evidence for heterodonty in the species T. platyodon, with unicarinate mesial teeth likely playing a role in prey capture and labiolingually compressed, bicarinate distal teeth likely involved in prey processing. This type of heterodonty appears to be convergent with a series of other marine amniotes including early cetaceans. Overall, the species currently referred to as the genus Temnodontosaurus show a range of craniodental configurations allowing prey to be captured and processed in different ways - for example, T. eurycephalus has a deep snout and relatively small bicarinate teeth likely specialised for increased wound infliction and grip-and-tear feeding, whereas T. platyodon has a more elongate yet robust snout and larger teeth and may be more adapted for grip-and-shear feeding. These results suggest the existence of niche partitioning at higher trophic levels in Early Jurassic ichthyosaurians and have implications for future work on the taxonomy of this wastebasket genus, as well as for research into the ecology of other extinct megapredatory marine tetrapods.
Collapse
Affiliation(s)
- R F Bennion
- Evolution & Diversity Dynamics Lab, Université de Liège, Liège, Belgium
- OD Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - E E Maxwell
- Staatliches Museum für Naturkunde Stuttgart, Stuttgart, Germany
| | - O Lambert
- OD Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - V Fischer
- Evolution & Diversity Dynamics Lab, Université de Liège, Liège, Belgium
| |
Collapse
|
2
|
Velez-Juarbe J. New heterodont odontocetes from the Oligocene Pysht Formation in Washington State, U.S.A., and a reevaluation of Simocetidae (Cetacea, Odontoceti). PeerJ 2023; 11:e15576. [PMID: 37377790 PMCID: PMC10292202 DOI: 10.7717/peerj.15576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 05/25/2023] [Indexed: 06/29/2023] Open
Abstract
Odontocetes first appeared in the fossil record by the early Oligocene, and their early evolutionary history can provide clues as to how some of their unique adaptations, such as echolocation, evolved. Here, three new specimens from the early to late Oligocene Pysht Formation are described further increasing our understanding of the richness and diversity of early odontocetes, particularly for the North Pacific. Phylogenetic analysis shows that the new specimens are part of a more inclusive, redefined Simocetidae, which now includes Simocetus rayi, Olympicetus sp. 1, Olympicetus avitus, O. thalassodon sp. nov., and a large unnamed taxon (Simocetidae gen. et sp. A), all part of a North Pacific clade that represents one of the earliest diverging groups of odontocetes. Amongst these, Olympicetus thalassodon sp. nov. represents one of the best known simocetids, offering new information on the cranial and dental morphology of early odontocetes. Furthermore, the inclusion of CCNHM 1000, here considered to represent a neonate of Olympicetus sp., as part of the Simocetidae, suggests that members of this group may not have had the capability of ultrasonic hearing, at least during their early ontogenetic stages. Based on the new specimens, the dentition of simocetids is interpreted as being plesiomorphic, with a tooth count more akin to that of basilosaurids and early toothed mysticetes, while other features of the skull and hyoid suggest various forms of prey acquisition, including raptorial or combined feeding in Olympicetus spp., and suction feeding in Simocetus. Finally, body size estimates show that small to moderately large taxa are present in Simocetidae, with the largest taxon represented by Simocetidae gen. et sp. A with an estimated body length of 3 m, which places it as the largest known simocetid, and amongst the largest Oligocene odontocetes. The new specimens described here add to a growing list of Oligocene marine tetrapods from the North Pacific, further promoting faunistic comparisons across other contemporaneous and younger assemblages, that will allow for an improved understanding of the evolution of marine faunas in the region.
Collapse
Affiliation(s)
- Jorge Velez-Juarbe
- Department of Mammalogy, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| |
Collapse
|
3
|
Anatomical, Ontogenetic, and Genomic Homologies Guide Reconstructions of the Teeth-to-Baleen Transition in Mysticete Whales. J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09614-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
4
|
Peredo CM, Pyenson ND, Uhen MD. Lateral palatal foramina do not indicate baleen in fossil whales. Sci Rep 2022; 12:11448. [PMID: 35794235 PMCID: PMC9259611 DOI: 10.1038/s41598-022-15684-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 06/28/2022] [Indexed: 11/19/2022] Open
Abstract
Today's mysticetes filter-feed using baleen, a novel integumentary structure with no apparent homolog in any living mammal. The origins of filter-feeding and baleen can be informed by the fossil record, including rare instances of soft tissue preservation of baleen and also by potential osteological correlates of baleen. Lateral palatal foramina on the roof of the mouth have been proposed as potential osteological correlates of baleen and their presence in some tooth-bearing stem mysticetes has led to the hypothesis that these early mysticetes possessed both teeth and incipient baleen. Here, we test this hypothesis by examining lateral palatal foramina in both filter-feeding and non-filter-feeding cetaceans, including crown and stem odontocetes and in stem cetaceans (or archaeocetes). We also confirm the presence of lateral palatal foramina in 61 species of terrestrial artiodactyls. CT scanning demonstrates consistent internal morphology across all observed taxa, suggesting that the lateral palatal foramina observed in extant mysticetes are homologous to those of terrestrial artiodactyls. The presence of lateral palatal foramina in terrestrial artiodactyls and non-filter-feeding whales (odontocetes and archaeocetes) suggests that these structures are not unique predictors for the presence of baleen in fossil whales; instead, these structures are more probably associated with gingiva or other oral tissue.
Collapse
Affiliation(s)
- Carlos Mauricio Peredo
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA.
- Department of Marine Biology, Texas A&M University, Galveston, TX, USA.
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA.
| | - Nicholas D Pyenson
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
- Departments of Mammalogy and Paleontology, Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Mark D Uhen
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
- Department of Atmospheric, Oceanic, and Earth Sciences, George Mason University, Fairfax, VA, USA
| |
Collapse
|
5
|
Peredo CM, Pyenson ND. Morphological variation of the relictual alveolar structures in the mandibles of baleen whales. PeerJ 2021; 9:e11890. [PMID: 34395101 PMCID: PMC8327965 DOI: 10.7717/peerj.11890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 07/10/2021] [Indexed: 12/17/2022] Open
Abstract
Living baleen whales (mysticetes) are bulk filter feeders that use keratinous baleen plates to filter food from prey laden water. Extant mysticetes are born entirely edentulous, though they possess tooth buds early in ontogeny, a trait inherited from toothed ancestors. The mandibles of extant baleen whales have neither teeth nor baleen; teeth are resorbed in utero and baleen grows only on the palate. The mandibles of extant baleen whales also preserve a series of foramina and associated sulci that collectively form an elongated trough, called the alveolar groove. Despite this name, it remains unclear if the alveolar groove of edentulous mysticetes and the dental structures of toothed mammals are homologous. Here, we describe and quantify the anatomical diversity of these structures across extant mysticetes and compare their variable morphologies across living taxonomic groups (i.e., Balaenidae, Neobalaenidae, Eschrichtiidae, and Balaenopteridae). Although we found broad variability across taxonomic groups for the alveolar groove length, occupying approximately 60–80 percent of the mandible’s total curvilinear length (CLL) across all taxa, the relictual alveolar foramen showed distinct patterns, ranging between 15–25% CLL in balaenids, while ranging between 3–12% CLL in balaenopterids. This variability and the morphological patterning along the body of the mandible is consistent with the hypothesis that the foramina underlying the alveolar groove reflect relictual alveoli. These findings also lay the groundwork for future histological studies to examine the contents of these foramina and clarify their potential role in the feeding process.
Collapse
Affiliation(s)
- Carlos Mauricio Peredo
- Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington D.C., United States of America.,Earth and Environmental Science, University of Michigan - Ann Arbor, Ann Arbor, MI, United States of America.,Marine Biology, Texas A&M University - Galveston, Galveston, TX, United States of America
| | - Nicholas D Pyenson
- Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington D.C., United States of America.,Paleontology and Geology, Burke Museum of Natural History and Culture, Seattle, WA, United States of America
| |
Collapse
|
6
|
Ekdale EG, Deméré TA. Neurovascular evidence for a co-occurrence of teeth and baleen in an Oligocene mysticete and the transition to filter-feeding in baleen whales. Zool J Linn Soc 2021. [DOI: 10.1093/zoolinnean/zlab017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Extant baleen whales (Mysticeti) have a deciduous foetal dentition, but are edentulous at birth. Fossils reveal that the earliest mysticetes possessed an adult dentition. Aetiocetids, a diverse clade of Oligocene toothed mysticetes, have a series of small palatal foramina and associated sulci medial to the postcanine dentition. The openings have been homologized with lateral palatal foramina that transmit neurovascular structures to baleen in extant mysticetes, thereby implying a co-occurrence of teeth and baleen in aetiocetids. However, homology of the foramina and sulci have been questioned. Using CT-imaging, we report that the lateral palatal foramina of Aetiocetus weltoni are connected internally to the superior alveolar canal, which transmits neurovascular structures to baleen in extant mysticetes and to teeth in extant odontocetes. Furthermore, the lateral palatal foramina of Aetiocetus are separate from the more medially positioned canals for the greater palatine arterial system. These results provide critical evidence to support the hypothesis that the superior alveolar neurovasculature was co-opted in aetiocetids and later diverging mysticetes to serve a new function associated with baleen. We evaluate competing hypotheses for the transition from teeth to baleen, and explore the transition from raptorial feeding in early mysticetes to filter-feeding in extant species.
Collapse
Affiliation(s)
- Eric G Ekdale
- Department of Biology, San Diego State University, Campanile Drive, San Diego, CAUSA
- Department of Paleontology, San Diego Natural History Museum, El Prado, San Diego, CA, USA
| | - Thomas A Deméré
- Department of Paleontology, San Diego Natural History Museum, El Prado, San Diego, CA, USA
| |
Collapse
|
7
|
Shipps BK, Peredo CM, Pyenson ND. Borealodon osedax, a new stem mysticete (Mammalia, Cetacea) from the Oligocene of Washington State and its implications for fossil whale-fall communities. ROYAL SOCIETY OPEN SCIENCE 2019; 6:182168. [PMID: 31417706 PMCID: PMC6689636 DOI: 10.1098/rsos.182168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 05/30/2019] [Indexed: 06/10/2023]
Abstract
Baleen whales (mysticetes) lack teeth as adults and instead filter feed using keratinous baleen plates. They do not echolocate with ultrasonic frequencies like toothed whales but are instead known for infrasonic acoustics. Both baleen and infrasonic hearing are separately considered key innovations linked to their gigantism, evolutionary success and ecological diversity. The earliest mysticetes had teeth, and the phylogenetic position of many so-called toothed mysticetes remains debated, including those belonging to the nominal taxonomic groups Llanocetidae, Mammalodontidae and Aetiocetidae. Here, we report a new stem mysticete, Borealodon osedax gen. et sp. nov., from the Oligocene of Washington State, USA. Borealodon preserves multi-cusped teeth with apical wear; microCT scans of the inner ear indicate that the minimum frequency hearing limit of Borealodon was similar to mammalodontids. Borealodon is not recovered within a monophyletic Mammalodontidae nor a monophyletic Aetiocetidae; instead, it represents an unnamed lineage of stem Mysticeti, adding to the diversity of stem mysticetes, especially across the Rupelian-Chattian boundary. Furthermore, the presence of a putative chemosynthetic bivalve along with Osedax, a bone-boring annelid, found in association with the type specimen of Borealodon, offer more insights into the evolution of deep-sea whale-fall communities.
Collapse
Affiliation(s)
- B. K. Shipps
- Department of Atmospheric, Oceanic, and Earth Sciences, George Mason University, Fairfax, VA, USA
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
| | - Carlos Mauricio Peredo
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - Nicholas D. Pyenson
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
- Department of Paleontology and Geology, Burke Museum of Natural History and Culture, Seattle, WA, USA
| |
Collapse
|
8
|
Peredo CM, Pyenson ND, Marshall CD, Uhen MD. Tooth Loss Precedes the Origin of Baleen in Whales. Curr Biol 2018; 28:3992-4000.e2. [DOI: 10.1016/j.cub.2018.10.047] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 09/20/2018] [Accepted: 10/19/2018] [Indexed: 11/25/2022]
|