Robert-Ewan Fordyce - Academia.edu (original) (raw)

Papers by Robert-Ewan Fordyce

Acta Palaeontologica Polonica, 2014

The origins and evolutionary relationships of the pygmy right whale (Caperea marginata), the only... more The origins and evolutionary relationships of the pygmy right whale (Caperea marginata), the only living member of the Neobalaeninae, have been the subject of a long-standing debate. This phylogenetic uncertainty is compounded by a limited neobalaenine fossil record. Here, we report a Late Miocene mysticete mandible from Patagonia, Argentina, and provisionally refer it to Neobalaeninae, gen. et sp. indet. The new material represents only the third report of a fossil neobalaenine, and the first fossil occurrence of this lineage in the southwestern Atlantic. It is also the oldest specimen so far reported, thus corroborating the idea of an early divergence time for neobalaenines.

PeerJ, 2015

The Eocene history of cetacean evolution is now represented by the expansive fossil record of arc... more The Eocene history of cetacean evolution is now represented by the expansive fossil record of archaeocetes elucidating major morphofunctional shifts relating to the land to sea transition, but the change from archaeocetes to modern cetaceans is poorly established. New fossil material of the recently recognized family Eomysticetidae from the upper Oligocene Otekaike Limestone includes a new genus and species, Waharoa ruwhenua, represented by skulls and partial skeletons of an adult, juvenile, and a smaller juvenile. Ontogenetic status is confirmed by osteohistology of ribs. Waharoa ruwhenua is characterized by an elongate and narrow rostrum which retains vestigial alveoli and alveolar grooves. Palatal foramina and sulci are present only on the posterior half of the palate. The nasals are elongate, and the bony nares are positioned far anteriorly. Enormous temporal fossae are present adjacent to an elongate and narrow intertemporal region with a sharp sagittal crest. The earbones are ...

This study reviews the status of known fossil cetaceans and reported fossil cetacean-bearing loca... more This study reviews the status of known fossil cetaceans and reported fossil cetacean-bearing localities in Taiwan, including published and formerly un-reported specimens and localities from field investigations, national and private collections. There are 15 known localities of cetacean fossils, spanning Late Pleistocene (~0.01 Ma) to Late Miocene (~5.4 Ma), and four cetacean families are recognized: Delphinidae, Balaenopteridae, Balaenidae, and Eschrichtiidae. The occurrences indicate the potential to discover more cetacean-bearing localities and specimens in Taiwan. In particular, the cetacean fossils of Quaternary age can provide valuable information on the origins of the modern cetacean fauna around Taiwan.

Journal of Mammalian Evolution, 2015

Horopeta umarere is a new genus and species of extinct baleen whales from the Kokoamu Greensand (... more Horopeta umarere is a new genus and species of extinct baleen whales from the Kokoamu Greensand (early Chattian, Oligocene, in the range 25-27 Ma), Hakataramea Valley, New Zealand. The geological age makes Horopeta umarere one of the earliest named baleen whales. Phylogenetic analysis indicates that Horopeta umarere may be the earliest crown Mysticeti (the sister taxon to Cetotheriidae), or the sister species to the crown Mysticeti; it is clearly not a species of Eomysticetidae. Estimated skull and body length of Horopeta umarere are 1.5-1.6 m and 6.5-7.5 m, respectively. Horopeta umarere shows some features that are linked to gulp feeding as seen in living humpback and rorquals: laterally bowed and robust mandible, D-shaped to tear drop-shaped mandible in cr oss-section, and posterolaterally deflected triangular coronoid process of the mandible. The sternum of Horopeta umarere is elongate, rod-shaped, and dorsoventrally stout with bilateral anterior and posterior rugose protrusions, indicating the presence of at least two pairs of ribs or costal cartilages. The structure of the skull and mandible are consistent with the use of gulp feeding, but the sternal morphology and rib attachments suggest an early evolutionary stage in gulp feeding employment, where more complex rib attachment may restrict the volume of water and food taken in one gulp compared to living humpback and rorquals. Thus, the morphology of Horopeta umarere has implications for the emergence of gulp feeding in baleen whale evolution as well as the emergence of the crown Mysticeti.

Papers in Palaeontology, 2014

The published Oligocene record of mysticetes (baleen whales) is dominated by toothed mysticetes i... more The published Oligocene record of mysticetes (baleen whales) is dominated by toothed mysticetes in addition to the Eomysticetidae, the earliest known chaeomysticetes known only from the Oligocene. Formally recognized eomysticetids include examples from the Oligocene of South Carolina, USA (Eomysticetus), and Japan (Yamatocetus). A new fossil from the upper Oligocene Otekaike Limestone including a partial skull, periotic, tympanic bulla, mandible and some postcrania is here described as Tohoraata raekohao gen. et sp. nov. Tohoraata confirms the presence of an eomysticetid in New Zealand. Tohoraata raekohao is characterized by delicate frontal with numerous supraorbital foramina and sulci, relatively long exposure of the frontal and parietal along a transversely narrow intertemporal region, greatly enlarged temporal fossa, massive and anteriorly directed zygomatic process lacking a supramastoid crest, and a periotic with supe-rior process reduced to a low ridge with anterior and posterior apices. Cranial and postcranial fusion of elements, development of muscle attachments and osteohistology demonstrate that the T. raekohao holotype is an adult or possible subadult. Features of the tympanic bulla including a relatively wide bulla with a medial lobe that is transversely much wider than the lateral lobe, and a slightly posterolaterally facing exoccipital, permit referral of the fragmentary 'Mauicetus' waitakiensis of Marples into the genus Tohoraata, resulting in Tohoraata waitakiensis comb. nov. Description of T. raekohao and resolution of the relationships of the hitherto problematic Tohoraata waitakiensis indicates that several eomysticetids were present in the Southern Ocean during the Late Oligocene.

Biology letters, 2015

Ancestor-descendant relationships (ADRs), involving descent with modification, are the fundamenta... more Ancestor-descendant relationships (ADRs), involving descent with modification, are the fundamental concept in evolution, but are usually difficult to recognize. We examined the cladistic relationship between the only reported fossil pygmy right whale, †Miocaperea pulchra, and its sole living relative, the enigmatic pygmy right whale Caperea marginata, the latter represented by both adult and juvenile specimens. †Miocaperea is phylogenetically bracketed between juvenile and adult Caperea marginata in morphologically based analyses, thus suggesting a possible ADR-the first so far identified within baleen whales (Cetacea: Mysticeti). The †Miocaperea-Caperea lineage may show long-term morphological stasis and, in turn, punctuated equilibrium.

NAMMCO Scientific Publications, 2013

Teeth are important elements in studies of modern and fossil Cetacea (whales, dolphins), providin... more Teeth are important elements in studies of modern and fossil Cetacea (whales, dolphins), providing information on feeding habits, estimations of age and phylogenetic relationships. The growth layer groups (GLGs) recorded in dentine have demonstrated application for aging studies, but also have the potential to elucidate life history phenomena such as metabolic or physiologic events. Micro-Computed Tomography (Micro-CT) is a noninvasive and non-destructive technique that allows 3-dimensional study of mineralized tissues, such as human teeth, and their physical properties. Teeth from extant dolphins (Cetacea: Odontoceti) and some fossil odontocetes were scanned in a Skyscan 1172 Micro-CT desktop system. X-rays were generated at 100 kV and 100 µA for extant samples, and at 80kV and 124 µA for fossils. 0.5 mm thick aluminum and copper filters were used in the beam. Reconstructed images were informative for most extant species, showing a good resolution of the enamel layer, dentine and pulp cavity. Greyscale changes in the dentinal layers were not resolved enough to show GLGs. Visualization of the internal structure in fossil cetacean teeth depended on the degree of diagenetic alteration in the specimen; undifferentiated enamel and dentine regions probably reflect secondary mineralization. However, internal details were finely resolved for one fossil specimen, showing the enamel, internal layers of dentine and the pulp cavity. Micro-CT has been proven to be a useful tool for resolving the internal morphology of fossil and extant teeth of cetaceans before they are sectioned for other morphological analyses; however some methodological refinements are still necessary to allow better resolution of dentine for potential application in nondestructive age determination studies.

PloS one, 2015

The transition from terrestrial ancestry to a fully pelagic life profoundly altered the body syst... more The transition from terrestrial ancestry to a fully pelagic life profoundly altered the body systems of cetaceans, with extreme morphological changes in the skull and feeding apparatus. The Oligocene Epoch was a crucial time in the evolution of cetaceans when the ancestors of modern whales and dolphins (Neoceti) underwent major diversification, but details of dental structure and evolution are poorly known for the archaeocete-neocete transition. We report the morphology of teeth and ultrastructure of enamel in archaeocetes, and fossil platanistoids and delphinoids, ranging from late Oligocene (Waitaki Valley, New Zealand) to Pliocene (Caldera, Chile). Teeth were embedded in epoxy resin, sectioned in cross and longitudinal planes, polished, etched, and coated with gold palladium for scanning electron microscopy (SEM) observation. SEM images showed that in archaeocetes, squalodontids and Prosqualodon (taxa with heterodont and nonpolydont/limited polydont teeth), the inner enamel was o...

Journal of Anatomy, 2014

The nasal region of the skull has undergone dramatic changes during the course of cetacean evolut... more The nasal region of the skull has undergone dramatic changes during the course of cetacean evolution. In particular, mysticetes (baleen whales) conserve the nasal mammalian pattern associated with the secondary function of olfaction, and lack the sound-producing specializations present in odontocetes (toothed whales, dolphins and porpoises). To improve our understanding of the morphology of the nasal region of mysticetes, we investigate the nasal anatomy, osteology and myology of the southern right whale, Eubalaena australis, and make comparisons with other mysticetes. In E. australis external deflection surfaces around the blowholes appear to divert water off the head, and differ in appearance from those observed in balaenopterids, eschrichtiids and cetotherids. In E. australis the blowholes are placed above hypertrophied nasal soft tissues formed by fat and nasal muscles, a pattern also observed in balaenopterids (rorqual mysticetes) and a cetotherid (pygmy right whale, Caperea marginata). Blowhole movements are due to the action of five nasofacial muscles: dilator naris superficialis, dilator naris profundus, depressor alae nasi, constrictor naris, and retractor alae nasi. The dilator naris profundus found in E. australis has not been previously reported in balaenopterids. The other nasofacial muscles have a similar arrangement in balaenopterids, with minor differences. A novel structure, not reported previously in any mysticete, is the presence of a vascular tissue (rete mirabile) covering the lower nasal passage. This vascular tissue could play a role in warming inspired air, or may engorge to accommodate loss of respiratory space volume due to gas compression from increased pressure during diving.

Naturwissenschaften, 2014

Phylogenetic reconstructions are sensitive to the influence of ontogeny on morphology. Here, we u... more Phylogenetic reconstructions are sensitive to the influence of ontogeny on morphology. Here, we use foetal/ neonatal specimens of known species of living baleen whales (Cetacea: Mysticeti) to show how juvenile morphology of extant species affects phylogenetic placement of the species. In one clade (sei whale, Balaenopteridae), the juvenile is distant from the usual phylogenetic position of adults, but in the other clade (pygmy right whale, Cetotheriidae), the juvenile is close to the adult. Different heterochronic processes at work in the studied species have different influences on juvenile morphology and on phylogenetic placement. This study helps to understand the relationship between evolutionary processes and phylogenetic patterns in baleen whale evolution and, more in general, between phylogeny and ontogeny; likewise, this study provides a proxy how to interpret the phylogeny when fossils that are immature individuals are included. Juvenile individuals in the peramorphic acceleration clades would produce misleading phylogenies, whereas juvenile individuals in the paedomorphic neoteny clades should still provide reliable phylogenetic signals.

Palaeogeography Palaeoclimatology Palaeoecology, 2011

Fossil bioapatite may yield biogeochemical signals of paleoenvironments captured by living organi... more Fossil bioapatite may yield biogeochemical signals of paleoenvironments captured by living organisms. Bioapatite may be diagenetically altered, however, with ions added or removed post-mortem; such change is typically assessed using destructive and demanding techniques. Here, Raman spectroscopy is used as a rapid and non-destructive way to identify significant diagenetic alteration of fossil bioapatite. We found spectral parameters of phosphate symmetric stretching (ν 1 -PO 4 3− ) to be very sensitive to variations in apatite chemistry, particularly with respect to common diagenetic components (CO 3 2− , F − , Sr 2+ ). The Raman spectral parameters were subsequently applied to a set of modern (biogenic) and geologic (magmatic) apatite samples as potential endmembers for diagenetic alteration. Raman spectra were also collected from enamel and dentin (respectively resistant vs. alteration-prone) of fossil teeth. Phosphate-oxygen isotopic values from the same enamel-dentin samples were used as an index of alteration and provided definition of Raman spectral parameters as relates to diagenetic alteration. Diagenetically altered samples were characterised by spectra with ν 1 -PO 4 3− widths (at half maximum height) less than 13.0 cm − 1 , and ν 1 -PO 4 3− band positions greater than 964.7 cm − 1 . Raman spectroscopy is shown to have potential as a tool for pre-screening fossil apatite samples before further analyses.

The structure of the hippopotamus brain is virtually unknown because few studies have examined mo... more The structure of the hippopotamus brain is virtually unknown because few studies have examined more than its external morphology. In view of their semi-aquatic lifestyle and phylogenetic relatedness to cetaceans, the brain of hippopotamuses represents a unique opportunity for better understanding the selective pressures that have shaped the organization of the brain during the evolutionary process of adaptation to an aquatic environment. Here we examined the histology of the cerebral cortex of the pygmy hippopotamus (Hexaprotodon liberiensis) by means of Nissl, Golgi, and calretinin (CR) immunostaining, and provide a magnetic resonance imaging (MRI) structural and volumetric dataset of the anatomy of its brain. We calculated the corpus callosum area/brain mass ratio (CCA/BM), the gyrencephalic index (GI), the cerebellar quotient (CQ), and the cerebellar index (CI). Results indicate that the cortex of H. liberiensis shares one feature exclusively with cetaceans (the lack of layer IV across the entire cerebral cortex), other features exclusively with artiodactyls (e.g., the morphologiy of CRimmunoreactive multipolar neurons in deep cortical layers, gyrencephalic index values, hippocampus and cerebellum volumetrics), and others with at least some species of cetartiodactyls (e.g., the occipital cortex). The present study thus provides a comprehensive dataset of the neuroanatomy of H. liberiensis that sets the ground for future comparative studies including the larger Hippopotamus amphibius. ). In contrast, very little is known about the organization of the brain of hippopotamuses apart from its gross anatomy . Such a lack of information is probably due to both the restricted geographic distribution of the extant hippopotamuses within the African continent, and the small numbers of individuals comprising the worldwide population (estimated at 157,000 river hippopotamuses and a few thousand, at most, pygmy hippopotamuses; Eltringham, , 1993b) that make it difficult to obtain brain specimens. This is particularly true for the pygmy hippopotamus given its "Endangered" status in the International Union for Conservation of Nature (IUCN 2012) red list (IUCN Red List of Threatened Species, Version 2012.1). Here we describe the brain of H. liberiensis using magnetic resonance imaging (MRI) and a variety of histological approaches, including Nissl and Golgi staining, and immunohistochemistry. Moreover, we provide volumetric measurements of salient structures from MR images, as well as the values for the gyrencephalic index (GI), the cerebellar quotient (CQ) and the cerebellar index (CI). Finally, we report new findings on the distribution of von Economo neurons (VENs) first observed in this species in the insular cortex (Butti and Hof, 2010). Comparisons with cetaceans and other artiodactyls are made, when possible, to eludicate the evolutionary significance of certain neuroanatomical features.

Zoomorphology, 2013

Longitudinal and cross sections of teeth from 17 species of the Recent dolphins (Delphinoidea and... more Longitudinal and cross sections of teeth from 17 species of the Recent dolphins (Delphinoidea and Inioidea) were examined under scanning electron microscope to study the arrangement and ultrastructure of dental tissues with reference to phylogenetic and functional constraints. For most species, enamel had a simple bi-layered structure of radial enamel and an outer layer of prismless enamel. The outer prismless layer varied from 5 to 30 % of enamel thickness. The enamel of Burmeister's porpoise (Phocoena spinipinnis) was entirely prismless. The prisms had an open sheath; tubules and tuft-like structures were common at the enamel-dentine junction. Cetacean dentine was characterized by irregularly distributed dentinal tubules in a relatively homogenous dentinal matrix. Radial enamel was observed in all Delphinoidea and in the franciscana (Pontoporia blainvillei), whereas the Amazon river dolphin (Inia geoffrensis) had prisms organized in Hunter-Schreger bands. HSB in enamel are regarded as a device for resisting propagation of cracks. These may occur due to increased functional demands, possibly related to the hardness of the species diet. Simplification in tooth shape and reduced biomechanical demands plausibly explain the primitive radial organization among delphinoids and Pontoporia. The HSB structure in the Amazon river dolphin, similar to those of extinct archaeocetes, seems to have secondary functional implications. However, the distribution of HSB in more-basal odontocetes is too poorly known to judge whether the HSB of Inia are a retained plesiomorphic feature or convergence.

Proceedings of the Royal Society B: Biological Sciences, 2012

Paleontological Research, 2014

New Zealand Journal of Geology and Geophysics, 2011

Kaiikamaxwelli is a new species of archaic fossil penguin from the Kauru Formation (Waipawan–Mang... more Kaiikamaxwelli is a new species of archaic fossil penguin from the Kauru Formation (Waipawan–Mangaorapan, Early Eocene) of the southern Canterbury Basin, Waihao River, South Canterbury, New Zealand. Kaiikamaxwelli is represented by a well-preserved large and robust humerus, in which the broad m. scapulotricipitalis tendon sulcus, sigmoidal shaft and vestigial supracondylar process are similar to those of the basal penguin Waimanu,

Naturwissenschaften, 2013

The origin of the pygmy right whale (Caperea marginata) has long been one of the most vexing conu... more The origin of the pygmy right whale (Caperea marginata) has long been one of the most vexing conundrums of marine mammal evolution. The extremely disparate skeletal structure of Caperea and a patchy fossil record have left morphology and molecules at odds: whereas most morphological analyses ally Caperea with right whales (Balaenidae), most molecular studies instead suggest a close relationship with rorquals (Balaenopteridae) and grey whales (Eschrichtiidae). The morphological evidence supporting a Caperea-balaenid clade consists of several shared features of the skull and mandible, as traditionally observed in adult individuals. Here, we show that at least two of these features, the ascending process of the maxilla and the coronoid process, arise from substantially different precursors early during ontogeny and therefore likely do not represent genuine synapomorphies. Both of these juvenile morphologies have adult counterparts in the fossil record, thus indicating that the ontogenetic variation in the living species may be a genuine reflection of differing ancestral states. This new evidence contradicts previous morphological hypotheses on the origins of Caperea and may help to reconcile morphological and molecular evidence.

Marine Micropaleontology, 2012

Other uses, including reproduction and distribution, or selling or licensing copies, or posting t... more Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

Marine Mammal Science, 2013