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Author:	Robert Boessenecker
Date:	2025-12-31 12:00:00
Blog:	The Coastal Paleontologist
URL:	http://coastalpaleo.blogspot.com/2025/12/2025-in-review-advances-in-marine.html

Summary:

It's time for the end of the year roundup - for a while I wasn't so sure that 2025 was going to have that long a list of papers, but we ended up with over fifty, which is about average. Several new papers on Oligocene mysticetes came out, all of which were quite welcome - with the long-awaited redescription of Fucaia goedertorum by Ehecatl Hernandez-Cisneros and Jorge Velez-Juarbe, the new eomysticetid from Baja California Cochimicetus by Cielo Cedillo-Avila and colleagues, and of course, a new (albeit fragmentarily known) species of Janjucetus from Australia reported by Ruaridh Duncan and colleagues. I was also pleased to see several new taphonomic studies, mostly focusing on the organisms that feed on and inhabit marine mammals after death - such as the bone eating worm, Osedax. A book chapter published the first public images of the extraordinarily complete Louisiana specimen of the gigantic archaeocete Basilosaurus cetoides. We had some new papers on desmostylians and sirenians, but I think the real standout this year were papers on archaic odontocetes. My colleague Margot Nelson published three monographic papers from her dissertation research on squalodontids. One focused on redescribing Squalodon grateloupi from the lower Miocene of France, another on revising the taxonomy of the genus and family - a very brave endeavor - and lastly, redescribing the lovely Oligocene squalodontid Eosqualodon langewischei from Germany. In addition, Maximiliano Gaetan and colleagues published a new article describing the entire fossil record of Prosqualodon, and synonymized the Australian (er, Tasmanian) species Prosqualodon davidis with Prosqualodon australis from rocks of the same age in Patagonia. Another Patagonian whale, the early sperm whale Idiorophus patagonicus - was redescribed by Florencia Paolucci et al. A possible tooth of an even larger sperm whale, Livyatan, was reported from southern California; a new beaked whale, Flandriacetus, was reported from upper Miocene rocks of the North Sea - and new specimens and species of the Miocene odontocetes Chilcacetus and Kentriodon were reported. Surprisingly, only a couple of papers on fossil pinnipeds were published - including the surprisingly complete skeleton of Monachopsis by Pavlo Otriazhyi and colleagues from Ukraine. Papers I reviewed are marked by an asterisk. Now, the usual stipulations apply: I am likely to have missed something, but before you send me hate mail or suggest I include a publication, please double check that it wasn't covered last year. I include papers on this list based on the year they are first published online. If a paper is published online late in the year, but then included within a formal journal issue/volume in the following year, I leave it where it lies (just like in golf, I guess). Preprints, conference presentations, magazine articles, etc. do not count as they are not peer reviewed and do not represent the priorities of contemporary researchers. I am guaranteed to have missed papers in journals that do not post their papers online when first published (e.g. Cainozoic Research, Bolletino della Società Paleontologica Italiana). Once I've received pdfs for any missing papers, I'll include them! Papers must include subfossil or fossil marine mammals (studies on the skeletons of modern marine mammals don't count as paleontological research, even if executed by paleontologists). Multiple papers by the same author are not guaranteed to be in exact alphabetical order. And, lastly, no, I am not going to include complete references nor am I going to format them (and yes, I have been asked this before).    Amson and Boller – 3d Models related to the skull of Miocaperea pulchra  Pygmy right whales, represented by one extant species, Caperea marginata, are highly idiosyncratic baleen whales. Only one fossil of undisputable affinity is known to date, which is also the most complete, the holotype of Miocaperea pulchra (Bisconti, 2012; Marx et al., 2016). This specimen was found in theAguada de Lomas site (Pisco Formation, southern Peru) and is assumed to be upper Tortonian of age (Bianucci & Collareta, 2022; Bisconti, 2012). It has been brought to the State Museum of Natural History Stuttgart in the 80s (Bisconti, 2012), where it was mechanically prepared by one of us (MB). The holotypecomprises a sub-complete skull (missing the tympanic bullae) in two parts (See Table 1 and Fig. 1), as well as associated fragments of the mandible and baleen rack. Indeed, this is one of the exceptional cases of preservation yielded by the Pisco Formation, since baleens do not usually fossilize (Bosio et al., 2021).   Asai et al. - New evidence for the co-occurrence of two genera of Paleoparadoxiidae (Mammalia, Desmostylia) from the Middle Miocene of Japan: insights into taxonomic status and paleodiversity in Desmostylia. Desmostylia, an extinct order of marine mammals, includes two major families: Paleoparadoxiidae and Desmostylidae. Within Paleoparadoxiidae, three genera—Archaeoparadoxia, Paleoparadoxia, and Neoparadoxia—have been identified, with Paleoparadoxia being the only genus found on both coasts of the North Pacific Rim. In Akan, Hokkaido, Japan, one of the largest Paleoparadoxia fossil assemblages in the world has been discovered from the Middle Miocene Tonokita Formation. Previous studies suggested the presence of two congeneric species of Paleoparadoxia, while recent taxonomical revisions raise the possibility that two genera, Paleoparadoxia and Neoparadoxia, were present in Akan. Here, we describe three paleoparadoxiids specimens from Akan, which consist of two partial crania and a mandible. Based on morphological comparisons and phylogenetic analysis, we identified these specimens as Paleoparadoxia sp. and Neoparadoxia sp. This represents the first record of two genera of Paleoparadoxiidae in the same locality and horizon, with the potential to provide valuable insights into cladogenesis and morphological diversification within this family. In addition, the Akan specimens exhibit mosaic characteristics of Paleoparadoxia and Neoparadoxia, suggesting that a reassessment of their morphological features for taxonomic identification and phylogenetic analysis is required. To better understand species-level diversity patterns in Desmostylia, we conducted stage-binned analysis and richness curve analysis. Our analysis revealed three significant points in their diversification history: (1) Desmostylidae reached peak diversity at the Oligocene-Miocene boundary, coinciding with a glacial event; (2) Paleoparadoxiidae achieved peak diversity during the Middle Miocene global warming event; (3) both families declined in diversity and went extinct during the Middle to Late Miocene global cooling event. These findings indicate that desmostylian diversity could have been closely linked to climatic events, with the differing peak diversities of Paleoparadoxiidae and Desmostylidae reflecting their respective preferences for warmer and cooler climates. Our analysis provides a valuable baseline for understanding the diversity and evolutionary history of Desmostylia.   Baldanza et al. – Scavengers and opportunists at work in the deep sea: decapods, echinoids, and fishes. The early Pleistocene whale fall events recognized at the Bargiano site (southwestern Umbria, central Italy) provided the opportunity to document and reconstruct the community of scavengers and opportunists, vertebrates and invertebrates that gathered around cetacean remains. A rich fauna of ghost shrimps and brachyuran crustaceans (the most represented ones), teleost fish and other osteichthyes (i.e., Ophidiiformes and Sciaenidae), sharks, as well as some specimens of irregular echinoids, have been analysed. The occurrence of otoliths of the rare ophidiid fish Hoplobrotula orcianensis Schwarzhans, 1994 and the irregular echinoid Ova canalifera (Lamarck, 1816) are herein reported for the first time in early Pleistocene marine deposits from Umbria. Among the decapods, Jaxea nocturna Nardo, 1847, Goneplax rhomboides (Linnaeus, 1758), and Asthenognathus alleronensis Pasini, Garassino and De Angeli, 2017 are herein recorded, together with some additional well-preserved specimens of the previously reported Albaidaplax ispalensis Garassino, Pasini and Castro, 2013 and Chlinocephalus demissifrons Ristori, 1886. A shark teeth assemblage related to whale fall events is here documented. Moreover, the common tracks of burrowing organisms, referable to activity of crustaceans and echinoids, have been documented, allowing to reconstruct the life on the shallow seabed (maximum depth of about 150m) of scavengers and opportunists, which developed around a whale carcass. The identification of a specialized community (biome) of benthonics and nectonics, contributes to best define this peculiar bioenvironment, confirming the development at Bargiano and Montemoro sites of the four Ecological stages (Scavengers, Opportunists, Sulphophilic and Reef stages) linked to the whale fall events.    Berger et al. – The endocranial anatomy of protocetids and its implications for early whale evolution. Extant whales, dolphins, and porpoises result from a major macroevolutionary lifestyle transition that transformed land-dwelling cetaceans into fully aquatic species. This involved significant changes in sensory systems. The increase in brain size relative to body size (encephalization quotient) is an outstanding feature of modern cetaceans, especially toothed whales. Conversely, olfactory capabilities are assumed to have diminished along this transition, with airborne olfaction becoming less relevant. The extent and timing of olfactory reduction remain obscure due to challenges in accessing well-preserved fossil endocranial anatomy. This study shows that early cetaceans had already evolved an increased encephalization quotient, and that their olfactory apparatus was likely not yet under selective pressure leading to its reduction. We demonstrate this through an analysis of the extinct whale, Protocetus atavus, a member of the middle Eocene semiaquatic cetacean group Protocetidae. We provide the first documentation of its endocranial anatomy using high-resolution computed tomography and compare it to other early cetaceans as well as extant mammals. We conclude that cetaceans increased their brain size earlier than previously thought, while relying on a well-developed olfactory system at a time when they were still partly terrestrial.    Bisconti et al.– A new fossil from the Late Miocene of Piedmont (north-western Italy) sheds light on the evolution of the Cetotheriidae (Mammalia: Cetacea: Mysticeti). The baleen-bearing whale Albacetus salvifactus gen. et sp. nov. from the upper Tortonian of Piedmont (north-west Italy) is described herein and compared to an extended sample of mysticete cetaceans. The new taxon belongs to the Cetotheriidae sensu stricto family-rank clade and is closely related to the genera Herentalia, Brandtocetus, Ciuciulea, Adicetus and Tranatocetus from the North Atlantic, Mediterranean and Paratethys basins. The computed tomography (CT) scan of Albacetus salvifactus revealed several previously undescribed characters including the neurovascular characters of the rostrum and the virtual skull endocast. Based on the CT scan, the periotic of A. salvifactus was three-dimensionally reconstructed. The skull endocast revealed that the encephalization quotient (EQ) of A. salvifactus is in the 95% confidence interval of the EQ variation in mysticete cetaceans. Some functional areas of the brain were reconstructed based on specific impressions on the endocast surface, likely corresponding to the sylvian, ectosylvian, suprasylvian and ectolateralis fissures. Phylogenetic analysis revealed that Cetotheriidae sensu stricto is subdivided into two subclades: (1) a North Atlantic group and (2) a widespread group including Herpetocetus, Piscobalaena, Metopocetus and Cetotherium. Phylogenetic results suggest multiple invasions of the Paratethys by different cetotheriid groups. Comparative phylogenetic analyses showed that the monophyly of Caperea and Cetotheriidae sensu stricto, the monophyly of Plicogulae and the monophyly of Tranatocetidae are less parsimonious than the solution proposed herein, thereby reinforcing the monophyly of Balaenoidea, Balaenopteroidea and Thalassotherii.  Remarks: This paper is really about quite a lot more than just the new whale Albacetus. Mysticete researchers will want to digest this in detail since the study includes a number of quite expansive 'meta' analyses of mysticete evolution, which is characteristic of Michelangelo's recent papers taking more of a birds eye view of things. It's really quite excellent.  Note: the skull is a reconstruction; the skeleton is headless. Bisconti et al. – A new Pliocene sperm whale from Vigliano D'Asti, Piedemont, Northwest Italy. A new sperm whale species is described from the late Zanclean (Early Pliocene) of Piedmont, northwest Italy, based on a partial vertebral column and parts of the forelimb. The new taxon, Eophyseter damarcoi gen. nov. sp. nov., is characterized by elongated vertebral centra in the thoracic and lumbar regions of the vertebral column, wider and higher articular facets for the occipital condyles in the atlas, elliptical and dorsoventrally compressed posterior articular facet of the axis-bearing block, ulna with posteriorly convex margin. These characters distinguish Eophyseter damarcoi gen. nov. sp. nov.from other physeteroids and show that the vertebral proportions are differently arranged with respect to those of the extant sperm whale species. A phylogenetic analysis was performed to understand the relationships of Eophyseter damarcoi gen. nov. sp. nov. by adding 20 postcranial characters to a previous character x taxon matrix; it revealed that E. damarcoi gen. nov. sp. nov. forms a clade with P. macrocephalus. A taphonomic analysis suggested that the carcass of the holotype specimen of Eophyseter damarcoi gen. nov. sp. nov. was exploited by sharks and colonized by barnacles and molluscs; however, a quick burial prevented its total destruction by other invertebrates, as usual in the cetacean fossil record from the Pliocene of Piedmont. Bisconti et al. – Taphonomy and whale-fall analysis of the Tortonian baleen whales from the Stirone river, Emilia Romagna (northern Italy) The taphonomy of three balaenopterid skeletons is examined in order to describe the traces left by whale fall communities. The whale specimens include two partial skeletons and an isolated periotic; one of the partial skeletons is the holotype of Plesiobalaenoptera quarantellii, while the other two specimens represent two indeterminate balaenopterid species. The high number of trace fossils observed in these specimens was not observed in previous paleontological records of whale fall communities. The diversity of the trace fossils and the broad stratigraphic context in which the assemblages are included are investigated in order to investigate into the origin and evolution of the specialized whale fall communities since the Neogene. Macrophotographs, three-dimensional modeling from photogrammetry and laser scanner examinations of the specimens were used to analyze the diversity of trace fossils observed on the bones of the balaenopterids. Biostratigraphic analyses of the outcrops where the specimens were discovered were realized to constrain the ages of the specimens and to reconstruct paleoecological characters of the sites. Additionally, analyses of fish otoliths, mollusc shells and microfossils were carried out to refine the ecological setting of the sites. The partially articulated skeletons were affected by intense bioerosion and disarticulation that displaced several bones before the final burials.Trace fossils found on the whale bones include shark bite traces, Trypanites, Gastrochaenolites, ?Meandropolydora and Gnatulichnus ichnogenera documenting an intense exploitation of the energy reservoir represented by these carcasses. The biostratigraphic analysis of the site supports a Late Miocene (Upper Tortonian) age and shows presence of post-depositional processes. These included micro-faulting that acted on the whale bones and, in one case, provided forces able to deform a lumbar vertebra. Fish otoliths, mollusc shells and microfossils are consistent in supporting a c. 100 m deep inner shelf deposit. Absence of chemoautothrophic molluscs from the present whale falls confirms that water depth may be the main determinant of the presence of these highly specialized species, that flourish in anoxic environments, because decomposition at shallow depths may still occur in presence of high Oxygen concentrations. Those described herein are the most dense ensembles of traces documenting whale falls communities in the Late Miocene described up to now.   Bouaziz et al.– Morphological study of the anterior dentition in Raoellidae (Mammalia, Artiodactyla), new insight on their dietary habits. Raoellidae are small artiodactyls from the Indian subcontinent closely related to stem cetaceans. They bring crucial information to understand the early phase of the land-to-water transition in Cetacea. If they are considered to be partly aquatic, the question of their dietary habits remains partly understood due to their “transitional” morphology. Raoellidae are largely documented by their cheek teeth and getting a better knowledge of their anterior dentition constitutes an additional proxy to discuss their feeding habits. In this work, we document the anterior dentition of Indohyus indirae from an unprecedented sample of in situ and isolated teeth from the locality of East Aiji-2 in the Kalakot area (Rajouri district, India). We propose identification criteria for upper and lower incisors and canines in raoellids. Based on CT scan data, virtual reconstruction of in situ dentition, and identification of the isolated incisors and canines, we reconstruct a composite anterior dentition of Indohyus supported by the correspondence of wear facets between upper and lower teeth. This constitutes the first attempt at reconstruction of the anterior dentition of a raoellid. We show that the upper incisors are caniniform and very similar morphologically, whereas the lower incisors are pointed but remain incisiform and quite different from one another. We also describe noticeable intraspecific variation, at the level of upper canines, suggesting a potential sexual dimorphism in this species. Upper and lower incisors are recurved, with the upper incisor row arranged on a widely opened arch. Taken altogether the anterior dentition forms a grasping device, allowing the animal to capture and secure food, a characteristic shared with stem cetaceans. This would mark the first step towards the carnivorous diet in these peculiar artiodactyls.  Cedillo-Avila et al. - First record of an Eomysticetidae from the Late Oligocene at the Pilon locality, San Gregorio Formation, Baja California Sur, Mexico.  In the paleontological history of cetaceans, the group Chaeomysticeti represents the most basal lineage of baleen whales, as we know them today. Within this group, the family Eomysticetidae, which dates back to the Oligocene Epoch, has been identified in the Northern Hemisphere–specifically in the Pacific Ocean along the coasts of Japan and Mexico, as well as in the Atlantic Ocean in the United States. Additionally, fossils have been discovered in the Southern Hemisphere, particularly in New Zealand. In Baja California Sur, the discovery of Eomysticetidae fossils provides a more comprehensive record than previous findings and enhances our understanding of the relationship between the faunas of the Southern Hemisphere and those of the Northern Hemisphere. So far, one skull, two jaws and the left tympanic bulla have been uncovered, and the level of preservation is conducive to detailing important elements within the family, such as the temporal fossa, the intertemporal region, the length of the nasal bones and the secondary squamosal fossa, among others. Using phylogenetic tools such as TNT software, this anatomic evidence allows us to classify a new genus and species from the Oligocene Epoch.  Remarks: Another new eomysticetid! I was quite pleased to see this reported, and from Baja, no less! This is from the San Gregorio Formation, one of two major Oligocene cetacean bearing units in Baja (the other being the El Cien Formation, which you are going to be hearing about MUCH MORE in the coming months). Unfortunately, as is the case for many Oligocene cetaceans from the Pacific Northwest, indurated concretions that aren't soluble make for challenging prepwork - and as a result, the highly informative earbones remain in situ and virtually nothing is known of the periotic. The tympanic bulla has been removed, and it does have some unique features - though many oth

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