[PaleoMammalogy • 2025] Megabalaena sapporoensis • A New member of a large and archaic balaenid (Mysticeti: Balaenidae) from the Late Miocene of Sapporo, Hokkaido, Japan partly fills a gap of Right Whale Evolution

Megabalaena sapporoensis

Tanaka, Kimura, Shinmura, Ohira & Furusawa, 2025

DOI: doi.org/10.26879/1549 

 Artwork by Tatsuya Shinmura 

ABSTRACT

The family Balaenidae (right whales) includes two genera and four extant species, all of which are endangered and giant animals measuring approximately 17 to 20 m in length. The history of the Balaenidae spans about 20 million years. Several small sized extinct balaenids from the Pliocene have been identified. However, half of this history remains unknown owing to a 9-million-year gap from 15.2 to 6.1 m.y.a. in the fossil record. A well-preserved fossil balaenid skeleton, designated SMAC 2731, from the Late Miocene approximately 9 m.y.a. in Sapporo, Hokkaido, Japan, is named as Megabalaena sapporoensis gen. et sp. nov. This specimen preserves the skull, periotics in situ, tympanic bullae, right mandible, basihyal-thyrohyal, right stylohyal, sternum, seven cervical vertebrae, nine thoracic vertebrae, and 16 more posterior vertebrae, rib fragments, scapulae, and left forelimb elements. All preserved vertebral epiphyses are fused, indicating that SMAC 2731 was physically mature. Notably, M. sapporoensis can be distinguished from other balaenids by its excavated orbit in dorsal view with a large postorbital process, dorsoventrally high anterior part of the involucrum of the tympanic bulla, long compound posterior process, high coronoid process and deeper subcondylar furrow of the mandible, incipient cervical fusion (C2+C3 only), and its slender forelimb bones, including the humerus, radius and ulna. Based on a bizygomatic width of 2.2 m, the estimated total length of the holotype of M. sapporoensis is 12.7 m. Overall, M. sapporoensis indicates that balaenids diversified prior to the Late Miocene.

   

Keywords: Balaenidae;  new genus;  new species;  Tortonian;  gigantism;  Japan

Forelimb elements of balaends. 
Megabalaena sapporoensis (A),
Charadrobalaena valentinae, outline taken from Bisconti et al. (2023) and is a mirror image (B),
Antwerpibalaena liberatlas, outline taken from Duboys de Lavigerie et al. (2020) and is a mirror image (C),
Eubalaena japonica, outline taken from Omura (1958) (D), and are not to scale.

  Images based on a 3D model showing preserved skull elements of SMAC 2731, Megabalaena sapporoensis. Deformations are not restored.

 Images based on a 3D model showing skull elements of SMAC 2731, Megabalaena sapporoensis in left lateral view (A) and dorsal view (B). Deformations are restored using 3D model editor by T. Shinmura. Settings are the same to Figure 3.

CETACEA Brisson, 1762

NEOCETI Fordyce and de Muizon, 2001

MYSTICETI Gray, 1864

CHAEOMYSTICETI Mitchell, 1989

BALAENIDAE Gray, 1825

Megabalaena gen. nov 

Type species. Megabalaena sapporoensis sp. nov.

Etymology. The generic name, Megabalaena , is named derived from ancient Greek megas meaning great, large and mighty, and the type genus name of the family Balaenidae.

 

Megabalaena sapporoensis sp. nov.

Locality and horizon. SMAC 2731 was found at a riverbed of Toyohira River in Sapporo City, Hokkaido, Japan, by Kazuhisa Mori on 10 October 2008: Latitude 42°58'1.24"N, longitude 141°13'18.01"E (Figure 1 and Figure 2). SMAC 2731 was found from the upper part of the Toyama Formation. At the fossil area, the diatomaceous siltstone Toyama Formation is distributed. Diatomaceous siltstone of the Toyama Formation is exposed at the type locality ...

Etymology. Named after the fossil locality, Sapporo City.

Diagnosis. Megabalaena sapporoensis is a member of the Balaenidae because it has a combination of these character states such as a posteriorly pointed anterior edge of the supraorbital process lateral to the ascending process of the maxilla with the skull in dorsal view (Character 31, state 0), laterally oriented postorbital process in dorsal view (Character 38, state 1), confluent posterior border of the zygomatic process of the squamosal and exoccipital in dorsal view (Character 67, state 1), dorsoventrally higher than long parietal in lateral view (Character 76, state 1), anterolaterally directed zygomatic process of the squamosal in dorsal view (Character 86, state 2), distinctly higher than long squamosal including the zygomatic and postglenoid processes (Character 92, state 1), short squamosal fossa (Character 96, state 1), foramen pseudovale opening posteriorly between the squamosal and pterygoid (Character 118, state 1), and posteriorly diverging basioccipital crests in ventral view (Character 125, state 0).

..

 Restoration of Megabalaena sapporoensis by Tatsuya Shinmura (Ashoro Museum of Paleontology).

Yoshihiro Tanaka, Toshiyuki Kimura, Tatsuya Shinmura, Hiroto Ohira, and Hitoshi Furusawa. 2025. A New member of a large and archaic balaenid from the Late Miocene of Sapporo, Hokkaido, Japan partly fills a gap of Right Whale Evolution.  Palaeontologia Electronica. 28(2): a37. DOI: doi.org/10.26879/1549 [August 2025]

palaeo-electronica.org/content/2025/5581-archaic-balaenid-from-japan

  

Plain Language Abstract: The right whale family (Balaenidae) includes four extant species in two genera such as the Balaena and Eubalaena, all of which are endangered and giant animals about 17 to 20 m in length. The history of the right whale group spans about 20 million years. Several small-sized extinct fossil right whales from the Pliocene have been identified. However, half of this history remains unknown owing to a 9-million-year gap from 15.2 to 6.1 million years ago in the fossil record. A well-preserved fossil right whale skeleton (SMAC 2731) from the late Miocene (approximately 9 m.y.a.) of Sapporo, Hokkaido, Japan, is named as the new species Megabalaena sapporoensis. This specimen preserves the skull, ear bones, right lower jaw, hyoid bones, sternum, back bones, ribs, scapulae, and left forelimb elements. All preserved vertebral epiphyses are fused, indicating that SMAC 2731 was physically mature. Notably, M. sapporoensis can be distinguished from other balaenids by its large postorbital process of the skull and unfused cervical vertebrae, except for the axis and third cervical vertebra, and its slender forelimb long bones, including the humerus, radius and ulna, which are about twice slenderer than these of extant balaenids. Based on a bizygomatic width of 2.2 m, the estimated total length of the holotype of M. sapporoensis is 12.7 m. Overall, M. sapporoensis enhances our understanding of balaenid diversity, suggesting that it expanded earlier than the late Miocene.

[PaleoMammalogy • 2025] Janjucetus dullardi • An Immature Toothed Mysticete from the Oligocene of Australia and insights into mammalodontid (Mysticeti: Mammalodontidae) Morphology, Systematics, and Ontogeny

 

Janjucetus dullardi 

Duncan, Rule, Park, Evans, Adams & Fitzgerald, 2025

DOI: doi.org/10.1093/zoolinnean/zlaf090 

  x.com/Inxcetus

Abstract

Mammalodontids are a clade of toothed mysticetes known only from the Chattian of south-eastern Australia and New Zealand. Despite three named species (Janjucetus hunderi, Mammalodon colliveri, and Mammalodon hakataramea), the majority of mammalodontid material, largely represented by isolated teeth and ear bones found within the Torquay Basin (Victoria, Australia), remains undescribed. Here we describe a new species of mammalodontid, Janjucetus dullardi sp. nov., from the Jan Juc Marl. The holotype was found stratigraphically lower than M. colliveri and has morphology consistent with an immature stage of growth, plus near-unworn dental morphology. We identify a correlation between occipital condyle breadth and bizygomatic width and propose equations that permit us to estimate bizygomatic width and, subsequently, a body size estimate similar to the smallest known toothed mysticetes of ∼2.05–2.18 m. Phylogenetic analysis recovers J. dullardi as sister to J. hunderi within a monophyletic mammalodontid clade in all analyses. It also provides support for Mammalodontidae within Mysticeti, sister to an Aetiocetidae + Chaeomysticeti clade. Finally, revised diagnoses of Mammalodon and Janjucetus incorporating newly recogniszed tympanic and periotic characters permit the identification of isolated ear bones and inference of ontogenetic variation within Janjucetus.

Australia, Cetacea, Janjucetus, Mammalodon, Mammalodontidae, Mysticeti, Oligocene, ontogeny, phylogeny

Artist’s reconstruction of the complete skull of Janjucetus dullardi.
Parts preserved in the fossil are white and light grey.

 Art by Ruairidh Duncan

Janjucetus dullardi sp. nov. 

Etymology: The species name dullardi honours Mr Ross Dullard, who discovered the holotype.

Type locality, horizon, and age: The holotype of Janjucetus dullardi (NMV P256471) was discovered near the town of Jan Juc in the lowest beds of the exposed onshore Jan Juc Marl at Half Moon Bay, southwest of Bird Rock (Fig. 2) at approximately 38°21′03″S, 144°18′02″E (precise locality details are available on request). The lithology of this cliff face describes a neritic, inner mid-shelf environment, which coarsens upwards, and with relatively low abundance of infauna (Li et al. 1999, McLaren et al. 2009). The type of J. dullardi was found near the base of this outcrop, exposed beneath a wave-eroded overhang, slightly above the level of the tidal beach sands (Fig. 1). The lithology of this horizon [unit 1 and 2 of Reeckmann (1979)] is one of a silty, sandy grey marl, interspersed with bedding planes of coarse silts to fine sandstones and rich in glauconite. A horizon ∼3 m above the fossil-producing layer was aged to 24.67 Mya using strontium isotope ratios (Korasidis et al. 2018). The top of the Bells Headland outcrop, interpreted as ∼2 m stratigraphically lower than the base of the Bird Rock outcrop, was aged to 26.05 Mya at a point correlated to ∼2.5 m below the horizon containing NMV P256471 using the same methodology (Korasidis et al. 2018). We therefore give an estimated age of this specimen of between 24.67 and 26.05 Mya (middle Chattian).

Diagnosis: We interpret J. dullardi as a mammalodontid on the basis of: the presence of an involucral concavity on the medial surface of the tympanic bulla ventral to the involucral ridge; a dorsomedially extended and anteroposteriorly wide crista transversa, which reaches to the level of the rim of the internal acoustic meatus medially (also seen in Salishicetus and Coronodon); and the presence of apicobasal ridges on both the buccal and lingual surfaces of the tooth crowns (also seen in Morawanocetus, ­Coronodon, and Llanocetus).

This specimen shares the following features with J. hunderi to the exclusion of Mammalodon: an obliquely truncated rather than squared anterior margin of the tympanic bulla; an inner posterior prominence of the tympanic bulla mediolaterally broader than the outer posterior prominence at the widest point of the bulla; periotic body and posterior process greatly exceed the posterior margin of the fenestra rotunda; anteroposterior and dorsoventral diameters of the anterior process of the periotic are subequal to one another; and the mandibular posterior postcanine teeth lack a distal accessory shelf near the base of the crown.

...

Janjucetus dullardi calf and mother swimming through the shallow seas, 25 million years ago.

Art by Ruairidh Duncan

 

Ruairidh J Duncan, James P Rule, Travis Park, Alistair R Evans, Justin W Adams and Erich M G Fitzgerald. 2025. An Immature Toothed Mysticete from the Oligocene of Australia and insights into mammalodontid (Cetacea: Mysticeti) Morphology, Systematics, and Ontogeny. Zoological Journal of the Linnean Society. 204(4); zlaf090. DOI: doi.org/10.1093/zoolinnean/zlaf090 [12 August 2025] 

  x.com/Inxcetus/status/1955406875228508362

https://theconversation.com/a-cornucopia-of-tiny-bizarre-whales-used-to-live-in-australian-waters-heres-one-of-them-262806

[PaleoMammalogy • 2024] Fucaia humilis • The Oldest mysticete (Mysticeti: Aetiocetidae) in the Northern Hemisphere

Fucaia humilis 

 Tsai, Goedert & Boessenecker, 2024

DOI: 10.1016/j.cub.2024.03.011 

 twitter.com/TSAI_NTU508

Highlights: 

• A new fossil mysticete is described from Washington State, USA

• This fossil represents the oldest known mysticete from the Northern Hemisphere

• The small body size contrasts with larger coeval whales in the Southern Hemisphere

• The coastal kelp ecosystem likely fostered the diversification of early whales

Summary

Extant baleen whales (Mysticeti) uniquely use keratinous baleen for filter-feeding and lack dentition, but the fossil record clearly shows that “toothed” baleen whales first appeared in the Late Eocene.1 Globally, only two Eocene mysticetes have been found, and both are from the Southern Hemisphere: Mystacodon selenensis from Peru, 36.4 mega-annum (Ma) ago and Llanocetus denticrenatus from Antarctica, 34.2 Ma ago. Based on a partial skull from the lower part of the Lincoln Creek Formation in Washington State, USA, we describe the Northern Hemisphere’s geochronologically earliest mysticete, Fucaia humilis sp. nov. Geology, biostratigraphy, and magnetostratigraphy places Fucaia humilis sp. nov. in the latest Eocene (ca. 34.5 Ma ago, near the Eocene/Oligocene transition at 33.9 Ma ago), approximately coeval with the oldest record of fossil kelps, also in the northeastern Pacific.5 This observation leads to our hypothesis that the origin and development of a relatively stable, nutrient-rich kelp ecosystem5,6 in the latest Eocene may have fostered the radiation of small-sized toothed mysticetes (Family Aetiocetidae) in the North Pacific basin, a stark contrast to the larger Llanocetidae (whether Mystacodon belongs to llanocetids or another independent clade remains unresolved) with the latest Eocene onset of the Antarctic Circumpolar Current in the Southern Hemisphere.7,8,9 Our discovery suggests that disparate mechanisms and ecological scenarios may have nurtured contrasting early mysticete evolutionary histories in the Northern and Southern hemispheres.

Systematics

Cetacea

Mysticeti

Aetiocetidae

Fucaia humilis sp. nov.

Diagnosis: Fucaia humilis sp. nov. shares with other species of Fucaia a newly identified synapomorphy: a shallow and rounded secondary squamosal fossa on the posterolateral margin of the squamosal (Figure 1). Eomysticetids possess a similar character, but the homology within Mysticeti remains uncertain. Furthermore, Fucaia humilis sp. nov. differs from all other aetiocetids and other Fucaia species by having the following unique character combination: a shorter intertemporal constriction exposed on the skull vertex; the presence of a distinct nuchal tubercle at the junction of parieto-squamosal suture and supraoccipital; a broadly rounded, dorsally low, and lobate coronoid process of the mandible; the presence of a postcoronoid elevation; and rounded anterior border of the tympanic bulla.

 Etymology: In Latin, humilis refers to humble in English, alluding to the previously unknown humble early mysticete evolution in the Northern Hemisphere.

Cheng-Hsiu Tsai, James L. Goedert and Robert W. Boessenecker. 2024. The Oldest mysticete in the Northern Hemisphere. DOI: 10.1016/j.cub.2024.03.011

  twitter.com/TSAI_NTU508/status/1773657177531486386 

[Paleontology • 2023] Giant Baleen Whales emerged from A Cold southern Cradle

Chaeomysticete mandible fragments NMV P218462 (Museums Victoria) from the Aquitanian–Burdigalian of South Australia.

in Rule, Duncan, Marx, Pollock, Evans & Fitzgerald, 2023.

 DOI: 10.1098/rspb.2023.2177

 twitter.com/Palaeo_JRule

Abstract

Baleen whales (mysticetes) include the largest animals on the Earth. How they achieved such gigantic sizes remains debated, with previous research focusing primarily on when mysticetes became large, rather than where. Here, we describe an edentulous baleen whale fossil (21.12–16.39 mega annum (Ma)) from South Australia. With an estimated body length of 9 m, it is the largest mysticete from the Early Miocene. Analysing body size through time shows that ancient baleen whales from the Southern Hemisphere were larger than their northern counterparts. This pattern seemingly persists for much of the Cenozoic, even though southern specimens contribute only 19% to the global mysticete fossil record. Our findings contrast with previous ideas of a single abrupt shift towards larger size during the Plio-Pleistocene, which we here interpret as a glacially driven Northern Hemisphere phenomenon. Our results highlight the importance of incorporating Southern Hemisphere fossils into macroevolutionary patterns, especially in light of the high productivity of Southern Ocean environments.

Keywords: Mysticeti, Chaeomysticeti, Southern Hemisphere, body size, gigantism

Systematic palaeontology

Cetacea Brisson 1762

Neoceti Fordyce & Muizon 2001

Mysticeti Gray 1864

Chaeomysticeti Mitchell 1989

Chaeomysticeti gen. et sp. indet.

Referred specimen. NMV P218462, symphyseal regions of both mandibles, plus fragments of the left premaxilla and maxilla.

Locality and horizon. NMV P218462 was found by F.A. Cudmore (on 15 February 1921) eroding from limestone cliffs on the east bank of the Murray River, opposite Wongulla, about 5 km south of Devon Downs, South Australia. ...

 

Conclusion: 

Baleen whales first evolved large body size in the Southern Hemisphere, perhaps facilitated by the onset of the ACC and high seasonal productivity in the Southern Ocean. Previous suggestions of an abrupt global Plio-Pleistocene shift towards mysticete gigantism are hampered by a strong collection bias against austral localities that obscures more gradual and regional trends. Medium-large mysticetes may have helped to engineer ocean ecosystems, albeit in a comparatively limited fashion, since the beginning of the Neogene. Further exploration of the Southern Hemisphere is crucial to constructing a truly global picture of the nature, timing and impacts of whale evolution.

James P. Rule, Ruairidh J. Duncan, Felix G. Marx, Tahlia I. Pollock, Alistair R. Evans† and Erich M.G. Fitzgerald. 2023. Giant Baleen Whales emerged from A Cold southern Cradle. Proc. R. Soc. B. 290: 20232177. DOI: 10.1098/rspb.2023.2177

 twitter.com/Palaeo_JRule/status/1737286061276242142

[PaleoMammalogy • 2021] Marzanoptera tersillae • A New Balaenopterid Genus and Species (Mysticeti: Balaenopteridae) from the Pliocene of Piedmont, north-west Italy

 

 Marzanoptera tersillae 

Bisconti, Damarco, Pavia, Sorce & Carnevale, 2021

  DOI: 10.1093/zoolinnean/zlaa131

  twitter.com/MickBisconti 

  twitter.com/ZoolJLinnSoc 

Abstract

Marzanoptera tersillae gen. & sp. nov., a new balaenopterid from the Pliocene of the Piedmont in north-west Italy, is described based on a partial skeleton and compared with other living and fossil baleen whales. Marzanoptera tersillae shares characters, such as the shape of the supraoccipital, glenoid fossa of the squamosal and zygomatic process of the squamosal, with ‘Balaenoptera’ bertae. We used a computed tomography scan to view parts of the skull that were otherwise impossible to observe, such as the periotic. A phylogenetic analysis based on 355 character states scored from 87 taxa revealed a well-resolved hypothesis of relationships for Balaenopteridae and a general phylogenetic hypothesis for chaeomysticetes. The monophyly of all superfamily- and family-rank clades and of crown balaenopterid species was confirmed. In addition, a monophyletic group including most basal thalassotherian taxa was recovered. The mollusc fauna associated with the specimen was autochtonous and constituted a residual fossil assemblage indicative of an environmental context located below the base of the storm wave, characterized by a low-energy hydrodynamic regimen. Many shark teeth have been found in close association or embedded within the bones, suggesting a possible scavenging action by two shark species on the whale carcass.

Keywords: Balaenopteridae, phylogeny, taphonomy, whale falls

SYSTEMATIC PALAEONTOLOGY 

Class Mammalia Linnaeus, 1758 

Order Cetacea Brisson, 1762 

Suborder Mysticeti Flower, 1865 

Infraorder Chaeomysticeti Mitchell, 1989 

Parvorder Balaenomorpha Geisler & Sanders, 2003 

Superfamily Thalassotherii Bisconti, Lambert & Bosselaers, 2013 

Epifamily Balaenopteroidea Gray, 1868 

Family Balaenopteridae Gray, 1864 

Genus Marzanoptera gen. nov. 

Etymology: The genus name is composed of Marzano-, shortened from San Marzanotto, the locality of the discovery of the holotype skeleton, and the Greek φτερό, wing, referring to the wide and long forearms of balaenopterid whales. 

Map showing the distribution of the bones of the holotype skeleton of  Marzanoptera tersillae. In this and subsequent figures, see ‘Anatomical abbreviations’ subsection of the main text for explanations of abbreviations. Scale bar: 500 mm.

Holotype skull of  Marzanoptera tersillae in lateral view.
 A, photographic representation of the skull in right lateral view.
B, anatomical interpretation.
C, photographic representation of the skull in left lateral view.
D, anatomical interpretation.

Scale bar: 10 cm.

Marzanoptera tersillae sp. nov.

Etymology: The fossil skeleton was discovered by Tersilla Argenta, for whom it was named. 

Holotype: Specimen 207.13307 of the inventory of EGPPA-MPTA institution in Asti. The specimen includes most of the skull, with one periotic in articulation, seven vertebrae and nine ribs. 

Michelangelo Bisconti, Piero Damarco, Marco Pavia, Barbara Sorce and Giorgio Carnevale. 2021. Marzanoptera tersillae, A New Balaenopterid Genus and Species from the Pliocene of Piedmont, north-west Italy. Zoological Journal of the Linnean Society. 192(4); 1253–1292. DOI: 10.1093/zoolinnean/zlaa131

  twitter.com/MickBisconti/status/1334956898982957060 

  twitter.com/ZoolJLinnSoc/status/1435166364029890567

[PaleoMammalogy • 2020] Antwerpibalaena liberatlas • A New Pliocene Right Whale (Cetacea, Balaenidae) from Belgium informs Balaenid Phylogeny and Function

Antwerpibalaena liberatlas

  Lavigerie, Bosselaers, Goolaerts, Park, Lambert & Marx, 2020

DOI: 10.1080/14772019.2020.1746422

 twitter.com/RBINSmuseum 

  naturalsciences.be 

Abstract

Right whales (Balaenidae) are the most distinctive family of extant baleen whales, thanks to their highly arched rostrum, tall lips and robust body shape. They are also the oldest, originating as much as 20 million years ago (Ma). Nevertheless, their fossil record is patchy and frequently understudied, obscuring their evolution. Here, we describe a new stem balaenid, Antwerpibalaena liberatlas, from northern Belgium, adding to the rich but historically problematic baleen whale assemblage of the Pliocene North Sea. Within right whales, Antwerpibalaena forms a clade with two previously described extinct genera, Balaenella and Balaenula. The holotype preserves much of the postcranial skeleton, and informs the emergence of typical balaenid traits like fused neck vertebrae and paddle-shaped flippers. Its size is intermediate between that of extant right whales and most of their extinct forebears revealing a more complex pattern of balaenid size evolution than previously thought.

 

Keywords: Balaenidae, gigantism, cervical vertebrae, ear bones, forelimb, phylogeny

    

Systematic palaeontology 

Cetacea Brisson, 1762 

Neoceti Fordyce & de Muizon, 2001 

Mysticeti Gray, 1864 

Balaenidae Gray, 1821 

Antwerpibalaena gen. nov. 

 

Derivation of name. Antwerp, after the city (Antwerpen in Flemish) that lends its name to the harbour area where the fossil was found and which has long been at the centre of Belgian cetacean research; balaena, Latin for whale.

Antwerpibalaena liberatlas sp. nov.

Derivation of name. From liber, Latin for free; and atlas, after the name of the first cervical vertebra. The latter is unfused in the holotype of the new species. 

Holotype. IRSNB M2325, comprising a fragmentary basicranium, both tympanoperiotics, the right auditory ossicles, both mandibles, parts of the hyoid apparatus, the right forelimb, all seven cervical vertebrae, five thoracic vertebrae, the sternum and several ribs. 

Occurrence. The type and only specimen came from the Kieldrecht Lock (previously known as Deurganckdoksluis, Port of Antwerp area) on the left bank of the river Scheldt, north-west of the city of Antwerp, Belgium (Fig. 1). The specimen derives from the base of the Oorderen Sands Member (Lillo Formation), dated to 3.21–2.76 Ma (Piacenzian, late Pliocene) based on its dinoflagellate cyst assemblage (Louwye et al. 2004; De Schepper et al. 2009). 

 Consensus tree showing all compatible groups arising from the Bayesian total evidence (molecular þ morphological data) analysis. Numbers next to nodes represent posterior probabilities, values below 50 are not shown. Grey shading within Balaenidae indicates extant species. Drawing of whale by Carl Buell.

   

Conclusions: 

 Antwerpibalaena liberatlas is a new, medium-sized (9.5–11.9 m) extinct balaenid from the Pliocene of Belgium. Its well-preserved postcranial remains provide novel insights into the evolution of extant balaenid anatomy and function, such as the emergence of a fused neck and paddle-shaped flippers. Its total body length falls between that of extant right whales and most extinct species, and points to a more complex pattern of body size evolution than previously thought. The Pliocene North Sea was home to a disparate balaenid assemblage, ranging from small species like Balaenella brachyrhynus to comparative giants like Eubalaena ianitrix. Despite its chequered history, the Belgian Pliocene fossil record holds great potential to illuminate cetacean evolution at a time of major global change.

 

Guillaume Duboys de Lavigerie, Mark Bosselaers, Stijn Goolaerts, Travis Park, Olivier Lambert and Felix G. Marx. 2020. New Pliocene Right Whale from Belgium informs Balaenid Phylogeny and Function.  Journal of Systematic Palaeontology. 18(14); 1141-1166. DOI: 10.1080/14772019.2020.1746422

 twitter.com/RBINSmuseum/status/1255774863819706380

naturalsciences.be/nl/news/item/19046

[PaleoMammalogy • 2019] Nehalaennia devossi • A New Balaenopterid Whale (Cetacea, Mysticeti) from the late Miocene of the Southern North Sea Basin and the Evolution of Balaenopterid Diversity

Nehalaennia devossi 

Bisconti​, Munsterman & Post, 2019  

   DOI: 10.7717/peerj.6915

Abstract 

Background:

Balaenopterid mysticetes represent the most successful family-rank group of this clade. Their evolutionary history is characterized by a rich fossil record but the origin of the living genera is still largely not understood. Recent discoveries in the southern border of the North Sea revealed a number of well preserved fossil balaenopterid whales that may help resolving this problem. In particular, skull NMR 14035 shares morphological characters with the living humpback whale, Megaptera novaeangliae and, for this reason, its characteristics are investigated here.

Methods:

The comparative anatomical analysis of the new specimen formed the basis of a new phylogenetic analysis of the Mysticeti based on a matrix including 350 morphological character states scored for 82 Operational Taxonomic Units. The stratigraphic age of the specimen was determined based on the analysis of the dinocyst assemblage recovered in the associated sediment. We assessed clade diversity in Balaenopteridae by counting the numbers of clades in given time intervals and then plotted the results.

Results: 

Nehalaennia devossi n. gen. et sp. is described for the first time from the late Tortonian (8.7–8.1 Ma) of the Westerschelde (The Netherlands). This new taxon belongs to Balaenopteridae and shows a surprisingly high number of advanced characters in the skull morphology. Nehalaennia devossi is compared to a large sample of balaenopterid mysticetes and a phylogenetic analysis placed it as the sister group of a clade including the genus Archaebalaenoptera. The inclusion of this fossil allowed to propose a phylogenetic hypothesis for Balaenopteridae in which (1) Eschrichtiidae (gray whales) represents a family of its own, (2) Balaenopteridae + Eschrichtiidae form a monophyletic group (superfamily Balaenopteroidea), (3) Cetotheriidae is the sister group of Balaenopteroidea, (4) living Balaenoptera species form a monophyletic group and (5) living M. novaeangliae is the sister group of Balaenoptera. Our work reveals a complex phylogenetic history of Balaenopteridae and N. devossi informs us about the early morphological transformations in this family. Over time, this family experienced a number of diversity pulses suggesting that true evolutionary radiations had taken place. The paleoecological drivers of these pulses are then investigated.

 Figure 3: Dorsal view of the holotype skull of Nehalaennia devossi (NMR 999100014035). (A) Photographic representation. (B) Interpretation. Scale bar equals 10 cm.

Systematic Paleontology

Mammalia Linneaus, 1758
Cetartiodactyla Montgelard, Caatzeflis & Douzery, 1997

Cetacea Brisson, 1762
Neoceti Fordyce & De Muizon, 2001

Mysticeti Flower, 1864
Chaeomysticeti Mitchell, 1989
Thalassotherii Bisconti, Lambert & Bosselaers, 2013

Balaenopteridae Gray, 1864

Nehalaennia new genus

Nehalaennia devossi new species

Holotype: Specimen 999100014035 of the collection of the Natuurhistorisch Museum Rotterdam.

Etymology: The genus name is one of the spellings of the name of the Keltic pagan goddess of the sea which was also accepted by Romans when they conquered what is now the most southern province of The Netherlands. The species name is given to honor Dr. John de Vos for his lifelong contribution to Dutch paleontology and his leading role in creating the unique bond and trust between Dutch professional and amateur paleontologists.
 
Differential diagnosis: Nehalaennia devossi differs from Archaebalaenoptera castriarquati in having a rounded anterior border of the supraoccipital, anterior half of the supraoccipital not strongly compressed transversely, widely concave posterior border of the maxilla, shorter and wider ascending process of the maxilla, significantly shorter nasal bones and anterior border of the supraorbital process of the frontal anterolaterally concave. It differs from Plesiobalaenoptera quarantellii in showing a lower superior portion of the periotic, shorter and wider ascending process of the maxilla, more slender lateral process of the maxilla with deeper antorbital notch, posterior end of the posterior process of the periotic more robust and round. It differs from ‘Megaptera’ hubachi in having a ventrally concave glenoid fossa of the squamosal with the postglenoid process projecting ventrally and forming a c. 90° angle with the zygomatic process of the squamosal, in having a rounded anterior border of the supraoccipital, and in lacking exposure of the alisphenoid in the temporal fossa. It differs from ‘Balaenoptera’ bertae in having a wider and rounder anterior border of the supraoccipital, in having an anterolaterally concave anterior border of the supraorbital process of the frontal, in having a vertically-oriented postglenoid process of the squamosal making the glenoid fossa of the squamosal more concave in lateral view. It differs from Incakujira anillodefuego in having a rounder and wider anterior border of the supraoccipital, in having a comparatively shorter and slender supraorbital process of the frontal and a comparatively shorter zygomatic process of the squamosal, in having the premaxilla terminating anteriorly to the nasal. It differs from ‘Megaptera’ miocaena in having a narrower anterior border of the supraoccipital, comparatively longer ascending process of the maxilla with ‘primary dorsal infraorbital foramina’, more concave glenoid fossa of the squamosal. It differs from Fragilicetus velponi in lacking a squamosal bulging into the temporal fossa, in having a wider anterior border of the supraoccipital, in having a less strongly protruding posterolateral corner of the exoccipital, in having a rounded dorsal border of the periotic. It differs from Protororqualus cuvieri in having a wider and rounder anterior border of the supraoccipital, in having shorter zygomatic process of the squamosal, in having a wider space between the posterior border of the maxilla and the anterior border of the supraorbital process of the frontal, and in having an anterolaterally concave anterior border of the supraorbital process of the frontal. The same differences are observed when Nehalaennia devossi is compared against ‘Balaenoptera’ cortesi var. portisi. It differs from Parabalaenoptera baulinensis in having shorter and wider ascending process of the maxilla, rounded supraoccipital and shorter nasal bones.

Nehalaennia devossi differs from the genus Balaenoptera in having a rounded anterior border of the supraoccipital, rounded posterior end of the ascending process of the maxilla, anterolaterally concave anterior border of the supraorbital process of the frontal, alisphenoid not exposed in the temporal fossa. It differs from Megaptera novaeangliae in having zygomatic process of the squamosal less diverging from the longitudinal axis of the skull, anterior border of the pars cochlearis of the periotic not strongly protruded, and more concave glenoid fossa of the squamosal in lateral view.

 Artistic reconstruction of Nehalaennia devossi shows two individuals during feeding upon schooling fishes. The leatherback turtle is used as a reference to show the hypothesized size of the rorqual. Credits for the illustration: Remie Bakker, Manimal Works, Rotterdam, The Netherlands.

Michelangelo Bisconti​, Dirk K. Munsterman and Klaas Post. 2019. A New Balaenopterid Whale from the late Miocene of the Southern North Sea Basin and the Evolution of Balaenopterid Diversity (Cetacea, Mysticeti). PeerJ. 7:e6915  DOI: 10.7717/peerj.6915

[PaleoMammalogy • 2018] Maiabalaena nesbittae • Tooth Loss Precedes the Origin of Baleen in Whales

Maiabalaena nesbittae 

 Peredo, Pyenson, Marshall & Uhen, 2018

  DOI: 10.1016/j.cub.2018.10.047

 Illustration: Alex Boersma (AlexBoersma.com)

 twitter.com/CMPeredo

Highlights

• Maiabalaena nesbittae is 33 million year old fossil baleen whale from Oregon

• Maiabalaena has neither teeth, nor baleen

• Early whales lost teeth entirely before the evolutionary origin of baleen

• Despite no teeth or baleen, these whales were effective suction feeders

Summary

Whales use baleen, a novel integumentary structure, to filter feed; filter feeding itself evolved at least five times in tetrapod history but demonstrably only once in mammals. Living baleen whales (mysticetes) are born without teeth, but paleontological and embryological evidence demonstrate that they evolved from toothed ancestors that lacked baleen entirely. The mechanisms driving the origin of filter feeding in tetrapods remain obscure. Here we report Maiabalaena nesbittae gen. et sp. nov., a new fossil whale from early Oligocene rocks of Washington State, USA, lacking evidence of both teeth and baleen. The holotype possesses a nearly complete skull with ear bones, both mandibles, and associated postcrania. Phylogenetic analysis shows Maiabalaena as crownward of all toothed mysticetes, demonstrating that tooth loss preceded the evolution of baleen. The functional transition from teeth to baleen in mysticetes has remained enigmatic because baleen decays rapidly and leaves osteological correlates with unclear homology; the oldest direct evidence for fossil baleen is ∼25 million years younger than the oldest stem mysticetes (∼36 Ma). Previous hypotheses for the origin of baleen are inconsistent with the morphology and phylogenetic position of Maiabalaena. The absence of both teeth and baleen in Maiabalaena is consistent with recent evidence that the evolutionary loss of teeth and origin of baleen are decoupled evolutionary transformations, each with a separate morphological and genetic basis. Understanding these macroevolutionary patterns in baleen whales is akin to other macroevolutionary transformations in tetrapods such as scales to feathers in birds.

Keywords: baleen, cetacea, filter-feeding, mysticeti, suction feeding

Figure 1. Cranial Elements of the Holotype of Maiabalaena nesbittae, USNM 314627.

Systematics 

Cetacea; Pelagiceti; 

Neoceti; Mysticeti; 

Maiabalaena nesbittae gen. et sp. nov. 

Etymology: Maiabalaena combines Maia-, meaning mother, and -balaena, meaning whale. Named for its phylogenetic position as basal to baleen-bearing mysticetes. The specific epithet nesbittae honors Dr. Elizabeth A. Nesbitt for her lifetime of contribution to paleontology of the Pacific Northwest and her mentorship and collegiality at the Burke Museum of Natural History and Culture in Seattle, Washington, USA.

 3D models of select specimens in lateral view with artistic reconstructions of their feeding modes:
 (B) Basilosaurus isis; (C) Coronodon havensteini; (D) Maiabalaena nesbittae; and (E) Balaenoptera musculus.

These panels illustrate the loss of a functional dentition, the intermediate phase with neither teeth nor baleen, and the subsequent origin of baleen. Illustrations are original artwork by Alex Boersma (www.alexboersma.com).

Figure 2. Phylogenetic Relationships of Stem Mysticetes Illustrating the Evolutionary Loss of Teeth and Subsequent Origin of Baleen Figure illustrates a composite phylogeny including results from this analysis (Figure S4) and recently published analyses.
(A) Time calibrated simplified phylogeny, with collapsed clade resolution for Mammalodontidae, Aetiocetidae and Eomysticetidae, and crown Mysticeti.
 (B–E) Colored bars indicate groups figured; gray bars indicate groups not figured. Panels (b–e) represent 3D models of select specimens in lateral view with artistic reconstructions of their feeding modes: (B) Basilosaurus isis; (C) Coronodon havensteini; (D) Maiabalaena nesbittae; and (E) Balaenoptera musculus. These panels illustrate the loss of a functional dentition, the intermediate phase with neither teeth nor baleen, and the subsequent origin of baleen. Illustrations are original artwork by Alex Boersma (www.alexboersma.com).

This is an artistic reconstruction of a mother and calf of Maiabalaena nesbittae nursing offshore of Oregon during the Oligocene, about 33 million years ago. While Maiabalaena would not have been able to chew or filter feed, muscle attachments on the bones of its throat indicate it likely had strong cheeks and a retractable tongue. These traits would have enabled it to suck water into its mouth, taking up fish and small squid in the process. The ability to suction feed would have rendered teeth, whose development requires a lot of energy to grow, unnecessary. The loss of teeth, then, appears to have set the evolutionary stage for the baleen, which the scientists estimate arose about 5 to 7 million years later.

 Illustration: Alex Boersma (www.alexboersma.com)

 Carlos Mauricio Peredo, Nicholas D. Pyenson, Christopher D. Marshall and Mark D. Uhen. 2018. Tooth Loss Precedes the Origin of Baleen in Whales. Current Biology.  DOI: 10.1016/j.cub.2018.10.047

 twitter.com/CMPeredo/status/1068179652135534592

 twitter.com/CMPeredo/status/1068229477375901696

 twitter.com/PyensonLab/status/1068215385613324290

twitter.com/NMNH/status/1068184159632453634

Whales Lost Their Teeth Before Evolving Hair-like Baleen in Their Mouths  si.edu/newsdesk/releases/whales-lost-their-teeth-evolving-hair-baleen-their-mouths via @Smithsonian

Toothless, 33-Million-Year-Old Whale Could Be an Evolutionary ‘Missing Link’  gizmodo.com/toothless-33-million-year-old-whale-could-be-an-evolut-1830739126 via @gizmodo