1
|
Abstract
Background Family Cetotheriidae sensu stricto and several closely related taxa comprise the Cetotherioidea and represent a lineage of Neogene baleen whales that includes the smallest edentulous baleen whales in Earth history. Most of known cetotheriids came from the Late Miocene to Quaternary, and the earliest records from the latest Middle Miocene. The Paratethys region shows a great diversity of Middle to Late Miocene cetotheriids. That includes nominative taxon of the family, Cetotherium rathkii, and this suggests that the earliest cetotheriids may have lived in that region. Materials and methods Here, Ciuciulea davidi, a new genus and species from the Middle Miocene of southeastern Europe, is described as the chronologically earliest and earliest diverging member of Cetotheriidae. Also, a new specimen of Otradnocetus, a basal Cetotherioidea sensu Gol'din & Steeman, 2015 is identified from the Late Miocene deposits of Caucasus and compared with Otradnocetus virodovi from the Middle Miocene of the same region. Results and discussion Ciuciulea davidi is a dwarf whale displaying primitive traits: posterior ends of facial bones forming a single transverse line, a narrow occipital shield, and a relatively long interparietal region. Meanwhile, it shares some cetotheriid apomorphies: posteriorly telescoped wedge-shaped facial bones and an ovoid tympanic bulla with shallow lateral and medial furrows, a short anterior lobe and a short sigmoid process. Phylogenetic analysis suggests that Parietobalaena and Otradnocetus are branches diverging before the clade Cetotheriidae + Neobalaenidae. This is confirmed by the stepwise evolution of the anatomy of the squamosal, mandible, and ear bones across these groups. The re-described juvenile specimen of Otradnocetus differs from O. virodovi in the more primitive anatomy of the mandible and the autapomorphic anatomy of the humerus. Records of the earliest cetotheriids and related taxa in the Paratethys support the idea that this could be the region where Cetotheriidae evolved before their worldwide dispersal and radiation.
Collapse
Affiliation(s)
- Pavel Gol'din
- Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, Kiev, Ukraine
| |
Collapse
|
2
|
Abstract
Neobalaenines are an enigmatic group of baleen whales represented today by a single living species: the pygmy right whale, Caperea marginata, found only in the Southern Hemisphere. Molecular divergence estimates date the origin of pygmy right whales to 22–26 Ma, yet so far there are only three confirmed fossil occurrences. Here, we describe an isolated periotic from the latest Miocene of Victoria (Australia). The new fossil shows all the hallmarks of Caperea, making it the second-oldest described neobalaenine, and the oldest record of the genus. Overall, the new specimen resembles C. marginata in its external morphology and details of the cochlea, but is more archaic in it having a hypertrophied suprameatal area and a greater number of cochlear turns. The presence of Caperea in Australian waters during the Late Miocene matches the distribution of the living species, and supports a southern origin for pygmy right whales.
Collapse
Affiliation(s)
- Felix G Marx
- Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,School of Biological Sciences, Monash University, Clayton, Victoria, Australia.,Palaeontology, Museums Victoria, Melbourne, Victoria, Australia
| | - Travis Park
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia.,Department of Life Sciences, Natural History Museum, London, United Kingdom
| | - Erich M G Fitzgerald
- Palaeontology, Museums Victoria, Melbourne, Victoria, Australia.,Department of Life Sciences, Natural History Museum, London, United Kingdom.,National Museum of Natural History, Smithsonian Institution, Washington, D.C., United States of America
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia.,Palaeontology, Museums Victoria, Melbourne, Victoria, Australia
| |
Collapse
|
3
|
Marx FG, Collareta A, Gioncada A, Post K, Lambert O, Bonaccorsi E, Urbina M, Bianucci G. How whales used to filter: exceptionally preserved baleen in a Miocene cetotheriid. J Anat 2017; 231:212-220. [PMID: 28542839 PMCID: PMC5522891 DOI: 10.1111/joa.12622] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2017] [Indexed: 11/30/2022] Open
Abstract
Baleen is a comb-like structure that enables mysticete whales to bulk feed on vast quantities of small prey, and ultimately allowed them to become the largest animals on Earth. Because baleen rarely fossilises, extremely little is known about its evolution, structure and function outside the living families. Here we describe, for the first time, the exceptionally preserved baleen apparatus of an entirely extinct mysticete morphotype: the Late Miocene cetotheriid, Piscobalaena nana, from the Pisco Formation of Peru. The baleen plates of P. nana are closely spaced and built around relatively dense, fine tubules, as in the enigmatic pygmy right whale, Caperea marginata. Phosphatisation of the intertubular horn, but not the tubules themselves, suggests in vivo intertubular calcification. The size of the rack matches the distribution of nutrient foramina on the palate, and implies the presence of an unusually large subrostral gap. Overall, the baleen morphology of Piscobalaena likely reflects the interacting effects of size, function and phylogeny, and reveals a previously unknown degree of complexity in modern mysticete feeding evolution.
Collapse
Affiliation(s)
- Felix G Marx
- School of Biological Sciences, Monash University, Clayton, Vic., Australia.,Geosciences, Museum Victoria, Melbourne, Vic., Australia.,D.O. Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium
| | - Alberto Collareta
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy.,Dottorato Regionale in Scienze della Terra Pegaso, Pisa, Italy
| | - Anna Gioncada
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Klaas Post
- Natuurhistorisch Museum Rotterdam, Rotterdam, The Netherlands
| | - Olivier Lambert
- D.O. Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium
| | - Elena Bonaccorsi
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Mario Urbina
- Departamento de Paleontología de Vertebrados, Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Giovanni Bianucci
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| |
Collapse
|
4
|
Marx FG, Bosselaers MEJ, Louwye S. A new species of Metopocetus (Cetacea, Mysticeti, Cetotheriidae) from the Late Miocene of the Netherlands. PeerJ 2016; 4:e1572. [PMID: 26835183 PMCID: PMC4734074 DOI: 10.7717/peerj.1572] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 12/16/2015] [Indexed: 11/20/2022] Open
Abstract
The family Cetotheriidae has played a major role in recent discussions of baleen whale phylogenetics. Within this group, the enigmatic, monotypic Metopocetus durinasus has been interpreted as transitional between herpetocetines and other members of the family, but so far has been restricted to a single, fragmentary cranium of uncertain provenance and age. Here, we expand the genus and shed new light on its phylogenetic affinities and functional morphology by describing Metopocetus hunteri sp. nov. from the Late Miocene of the Netherlands. Unlike the holotype of M. durinasus, the material described here is confidently dated and preserves both the tympanic bulla and additional details of the basicranium. M. hunteri closely resembles M. durinasus, differing primarily in its somewhat less distally expanded compound posterior process of the tympanoperiotic. Both species are characterised by the development of an unusually large fossa on the ventral surface of the paroccipital process, which extends anteriorly on to the compound posterior process and completely floors the facial sulcus. In life, this enlarged fossa may have housed the posterior sinus and/or the articulation of the stylohyal. Like other cetotheriids, Metopocetus also bears a well-developed, posteriorly-pointing dorsal infraorbital foramen near the base of the ascending process of the maxilla, the precise function of which remains unclear.
Collapse
Affiliation(s)
- Felix Georg Marx
- Department of Geology and Palaeontology, National Museum of Nature and Science , Tsukuba , Japan
| | - Mark E J Bosselaers
- Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Marine Vertebrates, Koninklijk Zeeuwsch Genootschap der Wetenschappen, Middelburg, The Netherlands
| | - Stephen Louwye
- Department Geology/Research Unit Palaeontology, Ghent University , Ghent , Belgium
| |
Collapse
|
5
|
Collareta A, Landini W, Lambert O, Post K, Tinelli C, Di Celma C, Panetta D, Tripodi M, Salvadori PA, Caramella D, Marchi D, Urbina M, Bianucci G. Piscivory in a Miocene Cetotheriidae of Peru: first record of fossilized stomach content for an extinct baleen-bearing whale. Naturwissenschaften 2015; 102:70. [PMID: 26553062 DOI: 10.1007/s00114-015-1319-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 10/13/2015] [Accepted: 10/22/2015] [Indexed: 10/22/2022]
Abstract
Instead of teeth, modern mysticetes bear hair-fringed keratinous baleen plates that permit various bulk-filtering predation techniques (from subsurface skimming to lateral benthic suction and engulfment) devoted to various target prey (from small invertebrates to schooling fish). Current knowledge about the feeding ecology of extant cetaceans is revealed by stomach content analyses and observations of behavior. Unfortunately, no fossil stomach contents of ancient mysticetes have been described so far; the investigation of the diet of fossil baleen whales, including the Neogene family Cetotheriidae, remains thus largely speculative. We report on an aggregate of fossil fish remains found within a mysticete skeleton belonging to an undescribed late Miocene (Tortonian) cetotheriid from the Pisco Formation (Peru). Micro-computed tomography allowed us to interpret it as the fossilized content of the forestomach of the host whale and to identify the prey as belonging to the extant clupeiform genus Sardinops. Our discovery represents the first direct evidence of piscivory in an ancient edentulous mysticete. Since among modern mysticetes only Balaenopteridae are known to ordinarily consume fish, this fossil record may indicate that part of the cetotheriids experimented some degree of balaenopterid-like engulfment feeding. Moreover, this report corresponds to one of the geologically oldest records of Sardinops worldwide, occurring near the Tortonian peak of oceanic primary productivity and cooling phase. Therefore, our discovery evokes a link between the rise of Cetotheriidae; the setup of modern coastal upwelling systems; and the radiation of epipelagic, small-sized, schooling clupeiform fish in such highly productive environments.
Collapse
|