Modern Whale Research Articles

First observed dolphin fall in the South China sea: Implications for the biogeography

Cetacean falls provide a large amount of organic matter to the deep ocean, an otherwise oligotrophic environment. These events are now believed to maintain endemic species and offer intermediate habitats for species in other deep-sea ecosystems. Only about 70 modern whale falls have been reported in the world's oceans to date. We discovered the first known dolphin fall in the South China Sea in March 2020, on the middle slope of the Zhongnan seamount. We set up a camera at the site to observe animals visiting the dolphin carcass for 30 consecutive days from March 29 to April 28, 2020 and made four additional HOV dives to the dolphin carcass. In total, we observed 14 visible megafauna species visiting this dolphin fall, including six fish species, five crustacean species, two echinoderm species, and one mollusk species, of which most were scavengers or predators. This was the first record of many of these taxa in the deep South China Sea. Furthermore, two bone-eating worms were found in a piece of the dolphin bone. The worms are identified as new species in the genus Osedax based on DNA analysis. The findings of this work suggest that cetacean falls occur frequently in the South China Sea and help to fill a knowledge gap regarding the biodiversity of cetacean falls in the West Pacific.

New sperm whale remains from the late Miocene of the North Sea and a revised family attribution for the small crown physeteroid Thalassocetus Abel, 1905

In spite of a continuously expanding physeteroid fossil record, our understanding of the origin and early radiation of the two modern sperm whale families Kogiidae Gill, 1871 (including the pygmy and dwarf sperm whales, Kogia spp.) and Physeteridae Gray, 1821 (including the great sperm whale, Physeter Linnaeus, 1758) remains limited, especially due to the poorly resolved phylogenetic relationships of a number of extinct species. Among those, based on fragmentary cranial material from the late early to middle Miocene of Antwerp (Belgium, North Sea basin), the small-sized Thalassocetus antwerpiensis Abel, 1905 has been recognized for some time as the earliest branching kogiid. The discovery of a new diminutive physeteroid cranium from the late Miocene (Tortonian) of Antwerp leads to the description and comparison of a close relative of T. antwerpiensis. Thanks to the relatively young ontogenetic stage of this new specimen, the highly modified plate-like bones making the floor of its supracranial basin could be individually removed, a fact that greatly helped deciphering their identity and geometry. Close morphological similarities with T. antwerpiensis allow for the reassessment of several facial structures in the latter; the most important reinterpretation is the one of a crest-like structure, previously identified as a sagittal facial crest, typical for kogiids, and here revised as the left posterolateral wall of the supracranial basin, comprised of the left nasal (lost in kogiids for which the postnarial region is known) and the left maxilla. Implemented in a phylogenetic analysis, the new anatomical interpretations result in the new Belgian specimen and T. antwerpiensis being recovered as sister-groups in the family Physeteridae. Consequently, the geologically oldest kogiids are now dated from the Tortonian, further extending the ghost lineage separating these early late Miocene kogiid records from the estimated latest Oligocene to earliest Miocene divergence of kogiids and physeterids.

The effects of cyclododecane and subsequent removal on δ15N, δ13C, and δ18O values in collagen and bioapatite of a modern bone

Applying consolidants to bone material in museum collections often is necessary to stabilize fragile specimens. However, this process can be difficult to reverse and may chemically alter the material, which may affect future biochemical analyses. Cyclododecane (CDD), a pliable solid that sublimates at room temperature, is a potential reversible alternative for temporary consolidation. This study examined the effects of CDD and Shell Cyclosol 53 (C53 – a solvent commonly used with CDD) on stable nitrogen, carbon, and oxygen isotope values in a modern whale rib. Different application methods (penetrating hot melt vs. surface heat spatula) and removal methods (low heat, ambient sublimation, and solvent) were tested in various combinations. The most effective method for removing CDD was low heat (65 °C); applying C53 also proved a viable option. All stable isotope values were unaffected by CDD application and solvent. No alteration was observed which suggests CDD does not affect the bone tissue structure, nor does it facilitate isotopic exchange or fractionation. This is an improvement over certain permanent consolidants which can alter bioapatite oxygen isotope values in particular. CDD is a viable temporary consolidant when further chemical analyses of bone tissue are desired.

Aegicetus gehennae, a new late Eocene protocetid (Cetacea, Archaeoceti) from Wadi Al Hitan, Egypt, and the transition to tail-powered swimming in whales.

Aegicetus gehennae is a new African protocetid whale based on a partial skull with much of an associated postcranial skeleton. The type specimen, Egyptian Geological Museum, Cairo [CGM] 60584, was found near the base of the early-Priabonian-age (earliest late Eocene) Gehannam Formation of the Wadi Al Hitan World Heritage Site in Egypt. The cranium is distinctive in having ventrally-deflected exoccipitals. The vertebral column is complete from cervical C1 through caudal Ca9, with a vertebral formula of 7:15:4:4:9+, representing, respectively, the number of cervical, thoracic, lumbar, sacral, and caudal vertebrae. CGM 60584 has two more rib-bearing thoracic vertebrae than other known protocetids, and two fewer lumbars. Sacral centra are unfused, and there is no defined auricular surface on the ilium. Thus there was no weight-bearing sacroiliac joint. The sternum is distinctive in being exceptionally broad and flat. The body weight of CGM 60584, a putative male, is estimated to have been about 890 kg in life. Long bones of the fore and hind limbs are shorter than expected for a protocetid of this size. Bones of the manus are similar in length and more robust compared to those of the pes. A log vertebral length profile for CGM 60584 parallels that of middle Eocene Maiacetus inuus through the anterior and middle thorax, but more posterior vertebrae are proportionally longer. Vertebral elongation, loss of a sacroiliac articulation, and hind limb reduction indicate that Aegicetus gehennae was more fully aquatic and less specialized as a foot-powered swimmer than earlier protocetids. It is doubtful that A. gehennae had a tail fluke, and the caudal flattening known for basilosaurids is shorter relative to vertebral column length than flattening associated with a fluke in any modern whale. Late protocetids and basilosaurids had relatively long skeletons, longer than those known earlier and later, and the middle-to-late Eocene transition from foot-powered to tail-powered swimming seemingly involved some form of mid-body-and-tail undulation.

Isotopes from fossil coronulid barnacle shells record evidence of migration in multiple Pleistocene whale populations

Migration is an integral feature of modern mysticete whale ecology, and the demands of migration may have played a key role in shaping mysticete evolutionary history. Constraining when migration became established and assessing how it has changed through time may yield valuable insight into the evolution of mysticete whales and the oceans in which they lived. However, there are currently few data which directly assess prehistoric mysticete migrations. Here we show that calcite δ18O profiles of two species of modern whale barnacles (coronulids) accurately reflect the known migration routes of their host whales. We then analyze well-preserved fossil coronulids from three different locations along the eastern Pacific coast, finding that δ18O profiles from these fossils exhibit trends and ranges similar to modern specimens. Our results demonstrate that migration is an ancient behavior within the humpback and gray whale lineages and that multiple Pleistocene populations were undertaking migrations of an extent similar to those of the present day.

The effects of cellulose nitrate treatment and organic solvent removal on δ13C, δ15N, and δ18O values of collagen and bioapatite in modern mammal bone

This study examines the effects of cellulose nitrate application and subsequent removal on stable isotope values in modern mammal bone which may be altered by addition of the consolidant in older museum archaeological and paleontological collections. Cellulose nitrate in the form of Duco cement was applied to modern whale and seal bones. Both treated bone and untreated controls were soaked in 100% acetone to remove cellulose nitrate and test effects of acetone on stable isotope values. Stable isotope values were measured in bone collagen (δ13Ccollagen, δ15Ncollagen) and bioapatite (δ13Cstructural carbonate, δ18Ostructural carbonate, δ18Ophosphate). The δ13Ccollagen, δ15Ncollagen, δ13Cstructural carbonate, and δ18Ophosphate values were unaltered by application of cellulose nitrate or exposure to acetone. The δ18Ostructural carbonate values were altered by exposure to cellulose nitrate in an unpredictable manner, most likely due to exchange of hydroxyl groups with differing isotope values. Care should be taken when using δ18Ostructural carbonate values from cellulose nitrate-treated bones as they may not represent an original isotope signature. Fourier transform infrared (FTIR) spectroscopy detected cellulose nitrate in all samples treated with the consolidant, including traces in bones soaked in 100% acetone (48 h) to remove it. This indicates that our procedure was not entirely adequate to fully remove cellulose nitrate. Although remnants of cellulose nitrate in treated bones apparently did not alter the isotope values, it is hereby suggested that future attempts to remove cellulose nitrate from bone include additional soaks or possibly sonication.

Ecological succession of a Jurassic shallow-water ichthyosaur fall.

After the discovery of whale fall communities in modern oceans, it has been hypothesized that during the Mesozoic the carcasses of marine reptiles created similar habitats supporting long-lived and specialized animal communities. Here, we report a fully documented ichthyosaur fall community, from a Late Jurassic shelf setting, and reconstruct the ecological succession of its micro- and macrofauna. The early ‘mobile-scavenger’ and ‘enrichment-opportunist’ stages were not succeeded by a ‘sulphophilic stage’ characterized by chemosynthetic molluscs, but instead the bones were colonized by microbial mats that attracted echinoids and other mat-grazing invertebrates. Abundant cemented suspension feeders indicate a well-developed ‘reef stage’ with prolonged exposure and colonization of the bones prior to final burial, unlike in modern whale falls where organisms such as the ubiquitous bone-eating worm Osedax rapidly destroy the skeleton. Shallow-water ichthyosaur falls thus fulfilled similar ecological roles to shallow whale falls, and did not support specialized chemosynthetic communities.

The Origin(s) of Whales

Whales are first found in the fossil record approximately 52.5 million years ago (Mya) during the early Eocene in Indo-Pakistan. Our knowledge of early and middle Eocene whales has increased dramatically during the past three decades to the point where hypotheses of whale origins can be supported with a great deal of evidence from paleontology, anatomy, stratigraphy, and molecular biology. Fossils also provide preserved evidence of behavior and habitats, allowing the reconstruction of the modes of life of these semiaquatic animals during their transition from land to sea. Modern whales originated from ancient whales at or near the Eocene/Oligocene boundary, approximately 33.7 Mya. During the Oligocene, ancient whales coexisted with early baleen whales and early toothed whales. By the end of the Miocene, most modern families had originated, and most archaic forms had gone extinct. Whale diversity peaked in the late middle Miocene and fell thereafter toward the Recent, yielding our depauperate modern whale fauna.

Exceptional occurrence of fossil baleen in shallow marine sediments of the Neogene Pisco Formation, Southern Peru

Fossil baleen is rare in the sedimentary record. This paper documents the exceptional occurrence of thirty seven fossil whale specimens with preserved baleen in the Neogene Pisco Formation during a transect survey in a limited area west of the Ica River Valley near the town of Ocucaje in southern Peru. The sedimentary layers consist of tuffaceous and diatomaceous sandstones, diatomaceous mudstones, and dolomites, deposited in a shallow marine embayment. Observations of modern whale carcasses on the seafloor and stranded individuals indicate that baleen detaches from the mouth of the whales very rapidly after death, and that bones deteriorate very rapidly as a result of scavenging activity and abrasion. In contrast, the bones of the Pisco Formation whales are exceptionally well preserved, and their baleen is often found in life position suspended from the rostrum. Sedimentary structures found associated with some skeletons indicate tidal and storm processes, suggesting that the environment was not anoxic. This exceptional occurrence of fossil baleen suggests early mineralization of the baleen attachment to the rostrum or rapid burial of the skeletons before any detachment or loss could occur.

Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing

The whale ear, initially designed for hearing in air, became adapted for hearing underwater in less than ten million years of evolution. This study describes the evolution of underwater hearing in cetaceans, focusing on changes in sound transmission mechanisms. Measurements were made on 60 fossils of whole or partial skulls, isolated tympanics, middle ear ossicles, and mandibles from all six archaeocete families. Fossil data were compared with data on two families of modern mysticete whales and nine families of modern odontocete cetaceans, as well as five families of noncetacean mammals. Results show that the outer ear pinna and external auditory meatus were functionally replaced by the mandible and the mandibular fat pad, which posteriorly contacts the tympanic plate, the lateral wall of the bulla. Changes in the ear include thickening of the tympanic bulla medially, isolation of the tympanoperiotic complex by means of air sinuses, functional replacement of the tympanic membrane by a bony plate, and changes in ossicle shapes and orientation. Pakicetids, the earliest archaeocetes, had a land mammal ear for hearing in air, and used bone conduction underwater, aided by the heavy tympanic bulla. Remingtonocetids and protocetids were the first to display a genuine underwater ear where sound reached the inner ear through the mandibular fat pad, the tympanic plate, and the middle ear ossicles. Basilosaurids and dorudontids showed further aquatic adaptations of the ossicular chain and the acoustic isolation of the ear complex from the skull. The land mammal ear and the generalized modern whale ear are evolutionarily stable configurations, two ends of a process where the cetacean mandible might have been a keystone character.

Sediment community structure around a whale skeleton in the deep Northeast Pacific: Macrofaunal, microbial and bioturbation effects

Chemoautotrophic communities on lipid-rich whale skeletons are known from a total of 16 modern and fossil sites in the deep Pacific Ocean. While the attached fauna of modern whale bones has been studied, the impact of whale falls on surrounding sediment assemblages remains largely unevaluated. Using the research submersible Alvin, we sampled the sediment community at distances of 0, 0.5, 1, 2, 4, and ∼100 m from the lipid-rich skeleton of a 21 m balaenopterid on the 1240 m seafloor in Santa Catalina Basin. When sampled in 1988 and 1991, the skeleton had been on the seafloor for >4 yr and supported a large attached chemoautotrophic assemblage. Sedimentary organic content, microbial biomass and bacterial abundance were not significantly different near the skeleton than in background sediments, and pore-water sulfide concentrations were only modestly elevated (to ⩽20 μM) adjacent to the bones. The species composition of infaunal macrobenthos near the skeleton was similar to that in background sediments, providing little evidence of a specialized enrichment and/or sulfophilic assemblage. Nonetheless, macrofaunal abundance within 0.5 m of the skeleton was reduced by >40%, due to a decline in the paraonid polychaete Levinsenia oculata. The reduction in L. oculata (the community dominant) caused a sharp increase in rarefaction diversity near the skeleton. Bioturbation intensities, evaluated from 234Th profiles, were also dramatically reduced in sediments near the skeleton, as were rates of extracellular lipase activity. We postulate that reduced infaunal abundance and bioturbation near the skeleton resulted from the interference effects of vesicomyid clam-shell debris, and that the low bioturbation rates in turn limited extracellular lipase activity. We conclude that whale skeletons, and the remains of their associated chemoautotrophic assemblages, may physically impact nearby sediment communities for years after the organic and sulfide enrichment effects of whale falls have dissipated, yielding changes in infaunal diversity and bioturbation.

Compound-specific approach to the δ 13C analysis of cholesterol in fossil bones

δ 13C values for cholesterol isolated from fossil animals, namely those of whales dated at 9735 ± 160 yr and 75000 ± 15000 yr B.P., are reported. Gas chromatography (GC) showed that 12 and 15 μg of cholesterol per gram dry weight of bone were recovered from the bones of these two fossil animals, respectively. Conventional gas chromatography-mass spectrometry (GC-MS) confirmed the identity of the ancient cholesterol and that the peaks separated by GC were of high purity. Gas chromatography-combustion-isotope ratio-mass spectrometry (GC-C-IRMS) of cholesterol recovered from the fossil specimens yielded δ 13C values that plotted within the range expected for the bulk fat of marine mammals. Significantly, the isotopic depletion between the cholesterol and collagen was similar for both ancient and modern whale bones, indicating reliable preservation of the δ 13C signal between the ancient cholesterol and the protein constituents. The potential to derive δ 13C values from individual lipids, for which the carbon skeletons are completely unaffected by decay processes, significantly extends the scope of palaeodietary studies.

Variability in the preservation of the isotopic composition of collagen from fossil bone

Collagen from bone was prepared by several methods. For modern and well-preserved bone the δ 13 C and δ 15 N of collagen replicas obtained after HCl or EDTA demineralization were similar to those obtained with a gelatinization procedure. However, in more poorly preserved fossil bone the δ 13 C and δ 15 N varied among the different protein extracts. The yield of collagen obtained with EDTA demineralization was consistently higher than extraction procedures that used HCl. The δ 13 C of individual amino acids separated from the collagen of modern and fossil whale bone varied up to 17%., and the δ 15 N from the same amino acids ranged over 47%. The δ 13 C and δ 15 N of most amino acids clustered closely to the average of the HCl insoluble collagen. The δ 13 C of the major amino acid in collagen, glycine, differed from the average HCl insoluble collagen by approximately 8%. in the fossil whale and 14%. in the modern whale. The δ 15 N of glycine differed from the average HCl insoluble values by approximately 4%. in the fossil whale and 7%. in the modern whale. Thus, diagenetic changes that alter the ratio of glycine to other amino acids in bone can be expected to perturb the values for carbon and nitrogen isotopes.