THE FOSSIL WHALE, <i>BALAENOPTERA DAVIDSONII</i> (COPE 1872), WITH A REVIEW OF OTHER NEOGENE SPECIES OF BALAENOPTERA (CETACEA: MYSTICETI)

Demeré, Thomas A.

doi:10.1111/j.1748-7692.1986.tb00136.x

Cited by 27 publications

(4 citation statements)

References 11 publications

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“…We placed Balaneoptera sp. (SDNHM 83695) as a sister taxon to Balaenoptera siberi (although not present in our sample), close to extant Megaptera novaeangliae as in Martin [ 99 ], Balaenoptera floridana as a sister taxon to Balaenoptera davidsonnii [ 100 , 101 ] (again, the latter species is not present in our sample), and Orycterocetus crocodilinus is placed in the physeterids according to Lambert et al [ 102 ]. We placed Globicephala sp .…”

Section: Methodssupporting

confidence: 58%

Wonky whales: the evolution of cranial asymmetry in cetaceans

et al. 2020

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Background Unlike most mammals, toothed whale (Odontoceti) skulls lack symmetry in the nasal and facial (nasofacial) region. This asymmetry is hypothesised to relate to echolocation, which may have evolved in the earliest diverging odontocetes. Early cetaceans (whales, dolphins, and porpoises) such as archaeocetes, namely the protocetids and basilosaurids, have asymmetric rostra, but it is unclear when nasofacial asymmetry evolved during the transition from archaeocetes to modern whales. We used three-dimensional geometric morphometrics and phylogenetic comparative methods to reconstruct the evolution of asymmetry in the skulls of 162 living and extinct cetaceans over 50 million years. Results In archaeocetes, we found asymmetry is prevalent in the rostrum and also in the squamosal, jugal, and orbit, possibly reflecting preservational deformation. Asymmetry in odontocetes is predominant in the nasofacial region. Mysticetes (baleen whales) show symmetry similar to terrestrial artiodactyls such as bovines. The first significant shift in asymmetry occurred in the stem odontocete family Xenorophidae during the Early Oligocene. Further increases in asymmetry occur in the physeteroids in the Late Oligocene, Squalodelphinidae and Platanistidae in the Late Oligocene/Early Miocene, and in the Monodontidae in the Late Miocene/Early Pliocene. Additional episodes of rapid change in odontocete skull asymmetry were found in the Mid-Late Oligocene, a period of rapid evolution and diversification. No high-probability increases or jumps in asymmetry were found in mysticetes or archaeocetes. Unexpectedly, no increases in asymmetry were recovered within the highly asymmetric ziphiids, which may result from the extreme, asymmetric shape of premaxillary crests in these taxa not being captured by landmarks alone. Conclusions Early ancestors of living whales had little cranial asymmetry and likely were not able to echolocate. Archaeocetes display high levels of asymmetry in the rostrum, potentially related to directional hearing, which is lost in early neocetes—the taxon including the most recent common ancestor of living cetaceans. Nasofacial asymmetry becomes a significant feature of Odontoceti skulls in the Early Oligocene, reaching its highest levels in extant taxa. Separate evolutionary regimes are reconstructed for odontocetes living in acoustically complex environments, suggesting that these niches impose strong selective pressure on echolocation ability and thus increased cranial asymmetry.

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Section: Methodssupporting

confidence: 58%

Wonky whales: the evolution of cranial asymmetry in cetaceans

et al. 2020

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“…Despite the increase in maximum body size among mysticetes and apparently coincidental extinction of Otodus megalodon during the Pliocene, numerous small-bodied archaic mysticetes persisted into the Pliocene (Bouetel & Muizon, 2006; Whitmore & Barnes, 2008; Collareta et al, 2017) and even Pleistocene (Boessenecker, 2013a), complicating this relationship. A modal extinction date of 3.6 for Otodus megalodon pre-dates the extinction of certain dwarf mysticetes such as Balaenula (Piacenzian-Gelasian; Barnes, 1977), Herpetocetus (Calabrian-Ionian; Boessenecker, 2013b) and various dwarf balaenopterids (Deméré, 1986; Boessenecker, 2013a). Indeed, further study of rare late Pliocene marine mammals is necessary to further elucidate potential competition with Otodus megalodon , extinctions, and faunal dynamics (Pimiento et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

The Early Pliocene extinction of the mega-toothed sharkOtodus megalodon: a view from the eastern North Pacific

Boessenecker

Ehret

Long

et al. 2019

PeerJ

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The extinct giant shark Otodus megalodon is the last member of the predatory megatoothed lineage and is reported from Neogene sediments from nearly all continents. The timing of the extinction of Otodus megalodon is thought to be Pliocene, although reports of Pleistocene teeth fuel speculation that Otodus megalodon may still be extant. The longevity of the Otodus lineage (Paleocene to Pliocene) and its conspicuous absence in the modern fauna begs the question: when and why did this giant shark become extinct? Addressing this question requires a densely sampled marine vertebrate fossil record in concert with a robust geochronologic framework. Many historically important basins with stacked Otodus-bearing Neogene marine vertebrate fossil assemblages lack well-sampled and well-dated lower and upper Pliocene strata (e.g., Atlantic Coastal Plain). The fossil record of California, USA, and Baja California, Mexico, provides such an ideal sequence of assemblages preserved within well-dated lithostratigraphic sequences. This study reviews all records of Otodus megalodon from post-Messinian marine strata from western North America and evaluates their reliability. All post-Zanclean Otodus megalodon occurrences from the eastern North Pacific exhibit clear evidence of reworking or lack reliable provenance; the youngest reliable records of Otodus megalodon are early Pliocene, suggesting an extinction at the early-late Pliocene boundary (∼3.6 Ma), corresponding with youngest occurrences of Otodus megalodon in Japan, the North Atlantic, and Mediterranean. This study also reevaluates a published dataset, thoroughly vetting each occurrence and justifying the geochronologic age of each, as well as excluding several dubious records. Reanalysis of the dataset using optimal linear estimation resulted in a median extinction date of 3.51 Ma, somewhat older than a previously proposed Pliocene-Pleistocene extinction date (2.6 Ma). Post-middle Miocene oceanographic changes and cooling sea surface temperature may have resulted in range fragmentation, while alongside competition with the newly evolved great white shark (Carcharodon carcharias) during the Pliocene may have led to the demise of the megatoothed shark. Alternatively, these findings may also suggest a globally asynchronous extinction of Otodus megalodon.

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“…portisi and the Protororqualus group including P. cuvieri, P. wilfriedneesi and the specimen UT PU 13842 that was described in detail by Caretto (1970) who assigned it to Balaenoptera acutorostrata cuvieri. This taxonomic decision was criticized by Deméré (1986) and Bisconti (2009) and a new description of this specimen is currently under preparation by one of us (M. Bisconti, 2020, in preparation).…”

Section: Phylogenetic Relationshipsmentioning

confidence: 99%

A new balaenopterid species from the Southern North Sea Basin informs about phylogeny and taxonomy of Burtinopsis and Protororqualus (Cetacea, Mysticeti, Balaenopteridae)

Bisconti

Bosselaers

2020

PeerJ

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Background An extensive radiation can be inferred among balaenopterid mysticetes in the last 10 million years based on a rich fossil record. Many extinct genera and species have been established in the past by the study of fossil rorquals from northern and southern hemispheres. In many cases, the new fossils are used to create new genera. However, in very recent times, new species of known genera have been described that help our understanding of the speciation processes and the biogeography of these whales. Here, a new species of balaenopterid whales is described in order to better understand the past diversity of Balaenopteridae and to analyze its paleobiogeographical implications. As the new species closely resembles a taxon established in the 19th century (i.e., Burtinopsis), a detailed analysis of this taxon was necessary to support the new taxonomic statements of this article. Methods A new partial skeleton including skull and earbones is described and compared to an extended sample of living and fossil mysticete species. A phylogenetic analysis including 355 character states scored in 88 taxa was performed to understand its relationships within the genus Protororqualus, to allow paleobiogeographic inferences and to better understand the relationships of Protororqualus within Balaenopteridae. Maximum parsimony analyses of character evolution were performed to understand morphological transformations within Balaenopteridae. The revision of Burtinopsis was carried out based on detailed descriptions and comparisons of the type materials that were figured and measured. Results Protororqualus wilfriedneesi sp. nov. was established based on a comparative analysis of the skull and earbone morphology. The specimen is dated back to the Zanclean (Lower Pliocene, between c. 5.3 and 3.6 Ma). A taphonomical study of the holotype skeleton revealed evidence of interactions with sharks and fishes before the definitive burial of the carcass. Based on the phylogenetic analysis, the monophyly of the genus Protororqualus was confirmed. Protororqualus wilfriedneesi sp. nov. was more derived than Protororqualus cuvieri suggesting that it resulted from an invasion of the North Sea Basin (and the North Atlantic ocean) from the Mediterranean basin. Several specimens from western and eastern sides of the Atlantic Ocean are described that suggest that Protororqualus wilfriedneesi had a trans-Atlantic distribution in the Pliocene.

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THE FOSSIL WHALE, BALAENOPTERA DAVIDSONII (COPE 1872), WITH A REVIEW OF OTHER NEOGENE SPECIES OF BALAENOPTERA (CETACEA: MYSTICETI)

Cited by 27 publications

References 11 publications

Wonky whales: the evolution of cranial asymmetry in cetaceans

Wonky whales: the evolution of cranial asymmetry in cetaceans

The Early Pliocene extinction of the mega-toothed sharkOtodus megalodon: a view from the eastern North Pacific

A new balaenopterid species from the Southern North Sea Basin informs about phylogeny and taxonomy of Burtinopsis and Protororqualus (Cetacea, Mysticeti, Balaenopteridae)

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