J G M Thewissen

J G M Thewissen
Northeast Ohio Medical University | NEOMED · Department of Anatomy and Neurobiology

About

210
Publications
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Introduction
Anatomy, Paleontology, and Embryology of mammals, in particular Cetacea (whales, dolphins, porpoises)
Additional affiliations
August 1993 - February 2016
Northeast Ohio Medical University
Position
  • Professor
August 1989 - July 1993
Duke University
Position
  • Research Associate

Publications

Publications (210)
Article
Full-text available
Most authors have identified two rapid increases in relative brain size (encephalization quotient, EQ) in cetacean evolution: first at the origin of the modern suborders (odontocetes and mysticetes) around the Eocene-Oligocene transition, and a second at the origin of the delphinoid odontocetes during the middle Miocene. We explore how methods used...
Article
Full-text available
(300 mots) We present the first description of the endocranial cast of the small raoellid artiodactyl Indohyus indirae. Raoellidae are sister group to Cetacea and the new morphological observations allow for outlining some of the early steps of the evolutionary history of the cetacean brain. The combination of primitive artiodactyl features and typ...
Article
Full-text available
A correction to this paper has been published: https://doi.org/10.1007/s10914-021-09554-9
Article
In a species of baleen whale, we identify olfactory epithelium that suggests a functional sense of smell and document the ontogeny of the surrounding olfactory anatomy. Whales must surface to breathe, thereby providing an opportunity to detect airborne odorants. Although many toothed whales (odontocetes) lack olfactory anatomy, baleen whales (mysti...
Article
Odontocete cetaceans have undergone profound modifications to their integument and sensory systems and are generally thought to lack specialized exocrine glands that in terrestrial mammals function to produce chemical signals (Thewissen & Nummela, 2008). Keenan-Bateman et al. (2016, 2018), though, introduced an enigmatic exocrine gland, associated...
Article
Full-text available
The present 3D Dataset contains the 3D models of the endocranial cast of two specimens of Indohyus indirae described in the article entitled “The endocranial cast of Indohyus (Artiodactyla, Raoellidae): the origin of the cetacean brain” (Orliac and Thewissen, 2021). They represent the cast of the main cavity of the braincase as well as associated i...
Chapter
The skull of the bowhead whale is composed of all the bones commonly found in mammals, although the shape of these bones is far from ordinary. Features related to feeding dominate the skull: there are no teeth, and the rostrum is long and curved, resembling a bow. The incisive and maxilla form a high arch that forms the origin of the baleen rack, a...
Chapter
In the late 1980s, annual carbon isotope cycles in the baleen plates of bowhead whales formed the basis of the first effective means of estimating bowhead age. However, the baleen aging method could only be used for aging subadult whales less than about 20 years old, due to wearing of the plates. Since then, seven additional methods of estimating t...
Chapter
The sensory biology of bowhead whales reflects features both related to their origin from land mammals and adaptations to their current environment, polar seas. There is anatomical and genomic evidence that bowheads have a sense of smell. Their sense of taste may be limited to detecting salty flavorants and there is no vomeronasal organ. They lack...
Chapter
The commercial hunt of the four stocks of bowhead whales by the nations of Europe and North America commenced in 1540 and came to an effective end at the start of World War I. At that time, all four stocks had been driven to near extinction. Whalers from many nations were involved, but the most important ones were those from Basque Country, the Net...
Chapter
The postcranial skeleton of bowhead whales was described in detail more than 100 years ago. The musculature of bowheads has not been studied in detail but matches that of other mysticetes in general features. In this chapter, we focus on some aspects of the skeleton that differs from that of other cetaceans. First, the skeleton of bowheads changes...
Chapter
The prenatal development of bowhead whales is poorly known, and no complete ontogenetic series exist. However, the available embryos and fetuses elucidate aspects of the development of the species, as well as that of all of mysticetes in general, and demonstrate the role of heterochrony in development. For instance, hair on the face of bowhead whal...
Chapter
We discuss the evolution, phylogenetic relations to right whales, and geographical distribution of bowhead whales. We summarize its relations to humans, including whaling by indigenous and European whalers, conservation efforts, and modern challenges with increased shipping, fishing, and climate change. We also discuss their adaptations that have u...
Chapter
Indigenous whalers know a great deal about the habits and environment of bowhead whales. That knowledge is essential for safe and effective hunting and has also been invaluable to scientific research and management of bowheads. Studies in Chukotka, Nunavut, and Alaska have documented Indigenous knowledge about bowhead whales. From the methods used...
Chapter
Bering–Chukchi–Beaufort Sea bowhead whales are born at about 4.2 m in length and 1000 kg, in lead systems along the NW Alaskan coast. Bowheads in the other northern stocks are also born in ice-covered seas. Maximum body lengths (standard measure) can reach 19 m. Regarding coloration: the skin is gray on neonates and young calves, and black on yearl...
Chapter
An understanding of the functional morphology of the bowhead whale continues to have significance for population management. This chapter first examines the anatomical features of the bowhead whale reproductive system, with an emphasis on the female. This is followed by a consideration of the functional parameters of the female reproductive cycle,...
Book
The Bowhead Whale: Balaena mysticetus: Biology and Human Interactions covers bowhead biology from their anatomy and behavior, to conservation, distribution, ecology and evolution. The book also discusses the biological and physical aspects of the Arctic ecosystem in which these whales live, with careful attention paid to the dramatic changes taking...
Article
Full-text available
The cetacean visual system is a product of selection pressures favoring underwater vision, yet relatively little is known about it across taxa. Previous studies report several mutations in the opsin genetic sequence in cetaceans, suggesting the evolutionary complete or partial loss of retinal cone photoreceptor function in mysticete and odontocete...
Chapter
Full-text available
The South Asian artiodactylArtiodactyla/Artiodactyl/ArtiodactylsgenusGenera/GenusIndohyus contains two species: I. indirae and I. major. Indohyus is the senior synonym of several other genera: RaoellaRaoellidae/Raoellid/Raoella, Kunmunella, MetkatiusMetkatius and HaqueinaHaqueina (in part). The dental morphology of a large collection of I. indirae...
Article
Full-text available
During the land-to-water transition in the Eocene epoch, the cetacean skeleton underwent modifications to accommodate life in the seas. These changes are well-documented in the fossil record. The forelimb transformed from a weight-bearing limb with mobile joints to a flipper with an immobile carpus. We used micro-CT imaging to assess evolutionary c...
Article
Full-text available
Bowhead whales are among the longest‐lived mammals with an extreme lifespan of about 211 years. During the first 25 years of their lives, rib bones increase in mineral density and the medulla transitions from compact to trabecular bone. Molecular drivers associated with these phenotypic changes in bone remain unknown. This study assessed expression...
Article
Orbital glands are found in many tetrapod vertebrates, and are usually separate structures, consisting of individual glands lying in the eyelids and both canthi of the orbit. In cetaceans, however, the orbital glandular units are less distinct and have been described by numerous authors as a single, periorbital mass. There are few histochemical and...
Article
The external acoustic meatus (EAM) of most baleen whales accumulates cellular debris annually in the lumen as whales age, forming a lamellated ear plug. The bowhead whale ear plug is formed from annually molting lining of the EAM as the entire epithelium releases at the level of the stratum basale during the spring migration. Epithelial regeneratio...
Article
Studying ontogeny in both extant and extinct species can unravel the mechanisms underlying mammal diversification and specialization. Among mammalian clades, Cetartiodactyla encompass species with a wide range of adaptations, and ontogenetic evidence could clarify longstanding debates on the origins of modern specialized families. Here, we study th...
Conference Paper
P1-23 Friday, Jan. 4 15:30 - 17:30 Role of Desmosomes in the Annual Molting of the External Acoustic Meatus Lining of the Bowhead Whale ( Balaena mysticetus): A Preliminary Study. REHOREK, SJ*; STIMMELMAYR, R; GEORGE, JC; SUYDAM, R; MCBURNEY, DM; THEWISSEN, JGM; Slippery Rock University, Slippery Rock; University of Alaska, Fairbanks; North Slope B...
Article
The embryology of cetaceans documents features that elucidate the interaction between form and function in modern species, as well as their evolution from extinct ones. Prenatal specimens of the dolphin Stenella attenuata demonstrate critical aspects of the embryonic and fetal development of cetaceans, the pharyngeal arches, ear ossicles, nasal ope...
Article
The external auditory meatus (EAM) in many species of mysticete whales is filled with a waxy ear plug. Though this lamellated structure is often used to age a whale, its formation and development remain undescribed. It is thought that growth layer groups (GLGs) are laid down annually, thereby increasing the size of this structure. Since some mystic...
Article
Few studies exist of the bowhead whale brain and virtually nothing is known about its cortical cytoarchitecture or how it compares to other cetaceans. Bowhead whales are one of the least encephalized cetaceans and occupy a basal phylogenetic position amongst mysticetes. Therefore, the bowhead whale is an important specimen for understanding the evo...
Article
Tympanic bullae and baleen plates from bowhead whales of the Western Arctic population were examined. Growth layer groups (GLGs) in the involucrum of the tympanic bone were used to estimate age of the whales, and compared to stable isotope signatures along transects of baleen plates and the involucrum. The involucrum of the tympanic bone consists o...
Article
Full-text available
Counts of Growth Layer Groups (GLGs) in the dentin of marine mammal teeth are widely used as indicators of age. In most marine mammals, observations document that GLGs are deposited yearly, but in beluga whales, some studies have supported the view that two GLGs are deposited each year. Our understanding of beluga life-history differs substantially...
Conference Paper
Orbital glands are found in many tetrapod vertebrates, and are usually separate structures: with individual glands lying in the eyelids and both canthi of the orbit. In cetaceans, however, the orbital glandular units are less distinct and have been described by numerous authors as a single, periorbital mass. It is presumed that these orbital glands...
Conference Paper
Annual shedding of ear wax is really a slough of skin.
Article
Full-text available
Cetaceans are the only mammals to have evolved hyperphalangy, an increase in the number of phalanges beyond the mammalian plesiomorphic condition of three phalanges per digit. In this study, cetaceans were used as a novel model to review previous studies of mammalian hyperphalangy and contribute new experimental evidence as to the molecular origins...
Article
The nasolacrimal duct (NLD) connects the orbital (often associated with the Deep Anterior Orbital gland: DAOG, a.k.a. Harderian gland) and nasal regions in many tetrapods. Adult cetaceans are usually said to lack an NLD, and there is little agreement in the literature concerning the identity of their orbital glands, which may reflect conflicting de...
Article
Full-text available
In utero, baleen whales initiate the development of several dozens of teeth in upper and lower jaws. These tooth germs reach the bell stage and are sometimes mineralized, but toward the end of prenatal life they are resorbed and no trace remains after birth. Around the time that the germs disappear, the keratinous baleen plates start to form in the...
Conference Paper
Full-text available
88.4 REHOREK, SJ*; HILLENIUS, WJ; THEWISSEN, JGM; Slippery Rock University, Slippery Rock, College of Charleston, Charleston, NEOMED, Rootstown; susan.rehorek@sru.edu Comparative anatomy of the nasolacrimal apparatus: the case of a dolphin (Stenella attenuata). The nasolacrimal duct (NLD) connects the orbital and nasal regions in many tetrapods. Ca...
Article
Full-text available
The processes of lipid deposition and utilization, via the gene leptin (Lep), are poorly understood in taxa with varying degrees of adipose storage. This study examines how these systems may have adapted in marine aquatic environments inhabited by cetaceans. Bowhead (Balaena mysticetus) and beluga whales (Delphinapterus leucas) are ideal study anim...
Article
Full-text available
The evolution of baleen constituted a major evolutionary change that made it possible for baleen whales to reach enormous body sizes while filter feeding on tiny organisms and migrating over tremendous distances. Bowhead whales (Balaena mysticetus) live in the Arctic where the annual cycle of increasing and decreasing ice cover affects their habita...
Data
Bowhead whale lengths and baleen plate lengths used in Fig 3. (XLSX)
Data
Rib bone density data used in Figs 4 and 5. (XLSX)
Data
Measurements (Fig 1) used in calculation of baleen rack surface area of bowhead whales used in Fig 3. (XLSX)
Article
Full-text available
While olfaction is one of the most important senses in most terrestrial mammals, it is absent in modern toothed whales (Odontoceti, Cetacea). Furthermore, behavioral evidence suggests that gustation is very limited. In contrast, their aquatic sistergroup, baleen whales (Mysticeti) retain small but functional olfactory organs, and nothing is known a...
Article
Full-text available
With the increase of human activity and corresponding increase in anthropogenic sounds in marine waters of the Arctic, it is necessary to understand its effect on the hearing of marine wildlife. We have conducted a baseline study on the spiral ganglion and Rosenthal's canal of the cochlea in beluga whales (Delphinapterus leucas) as an initial asses...
Article
Full-text available
Although modern baleen whales (Mysticeti) retain a functional olfactory system that includes olfactory bulbs, cranial nerve I and olfactory receptor genes, their olfactory capabilities have been reduced to a great degree. This reduction likely occurred as a selective response to their fully aquatic lifestyle. The glomeruli that occur in the olfacto...
Article
Full-text available
We studied the histology and morphometrics of the hairs of bowhead whales (Balaena mysticetus). These whales are hairless except for two patches of more than 300 hairs on the rostral tip of the lower lip and chin, the rostral tip of the upper lip, and a bilateral row of approximately ten hairs caudal to the blowhole. Histological data indicate that...
Article
Full-text available
In this paper we studied three related aspects of the ontogeny of the vertebral centrum of cetaceans and terrestrial mammals in an evolutionary context. We determined patterns of ontogenetic fusion of the vertebral epiphyses in bowhead whale (Balaena mysticetus) and beluga whale (Delphinapterus leucas), comparing those to terrestrial mammals and Eo...
Article
Cetacean evolution was shaped by an extraordinary land-to-sea transition in which the ancestors of whales became fully aquatic. As part of this transition, these mammals evolved unusually thick blubber which acts as a metabolic reservoir as well as an insulator and provides buoyancy and streamlining. This study describes blubber stratification and...
Preprint
Full-text available
Although modern baleen whales still possess a functional olfactory systems that includes olfactory bulbs, cranial nerve I and olfactory receptor genes, their olfactory capabilities have been reduced profoundly. This is probably in response to their fully aquatic lifestyle. The glomeruli that occur in the olfactory bulb can be divided into two non-o...
Preprint
Although modern baleen whales still possess a functional olfactory systems that includes olfactory bulbs, cranial nerve I and olfactory receptor genes, their olfactory capabilities have been reduced profoundly. This is probably in response to their fully aquatic lifestyle. The glomeruli that occur in the olfactory bulb can be divided into two non-o...
Book
A first-person account of the discoveries that brought to light the early fossil record of whales. As evidenced in the record, whales evolved from herbivorous forest-dwelling ancestors that resembled tiny deer to carnivorous monsters stalking lakes and rivers and to serpent like denizens of the coast.
Article
Full-text available
Anthracobunidae is an Eocene family of large mammals from south Asia that is commonly considered to be part of the radiation that gave rise to elephants (proboscideans) and sea cows (sirenians). We describe a new collection of anthracobunid fossils from Middle Eocene rocks of Indo-Pakistan that more than doubles the number of known anthracobunid fo...
Article
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Article
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Abstract Cetaceans are obligate aquatic mammals derived from terrestrial artiodactyls. The defining characteristic of cetaceans is a thick and dense lip (pachyosteosclerotic involucrum) of an ear bone (the tympanic). This unique feature is absent in modern terrestrial artiodactyls and is suggested to be important in underwater hearing. Here, we inv...
Article
Von Economo neurons (VENs) are specialized projection neurons with a characteristic spindle-shaped soma and thick basal and apical dendrites. VENs have been described in restricted cortical regions, with their most frequent appearance in layers III and V of the anterior cingulate cortex, anterior insula, and frontopolar cortex of humans, great apes...
Chapter
Full-text available
During the Eocene epoch, archaic cetaceans made the land-to-sea transition, giving rise to modern whales, dolphins, and porpoises. During this transition, the feeding apparatus of fossil remingtonocetines displayed morphologies that are distinct from other cetaceans, confounding straightforward interpretations of their feeding behaviors. This study...
Article
Full-text available
Protocetid cetaceans were first described from the Eocene of India in 1975, but many more specimens have been discovered since then and are described here. All specimens are from District Kutch in the State of Gujarat and were recovered in deposits approximately 42 million years old. Valid species described in the past include Indocetus ramani, Bab...
Article
Full-text available
A. Berta 2012. Return to the Sea: the Life and Evolutionary Times of Marine Mammals. University of California Press, Berkeley, California, 205 pp. ISBN 978-0-520-27057-2, price (hardbound), $31.26. Annalisa Berta is probably best known for having written Marine Mammals: Evolutionary Biology , the leading textbook and reference for her field, now i...
Article
Full-text available
The evolutionary success of mammals is rooted in their high metabolic rate. A high metabolic rate is sustainable thanks to efficient food processing and that in turn is facilitated by precise occlusion of the teeth and the acquisition of rhythmic mastication. These major evolutionary innovations characterize most members of the Class Mammalia. Ceta...
Article
Full-text available
Leptin is the primary hormone in mammals that regulates adipose stores. Arctic adapted cetaceans maintain enormous adipose depots, suggesting possible modifications of leptin or receptor function. Determining expression of these genes is the first step to understanding the extreme physiology of these animals, and the uniqueness of these animals pre...
Data
Standard curves for linearization tests of leptin and OB-RGRP. Linear regression lines illustrate differences in threshold cycles (Ct) between linear and circular plasmid standards for both leptin and OB-RGRP. Amplification efficiencies calculated using Efficiency = ((10∧–1/slope)–1) [27]. (TIF)
Data
Standard curves for qPCR background material tests of leptin and OB-RGRP. Linear regression lines illustrate no significant differences in threshold cycles (Ct) between yeast RNA and yeast cDNA background for both leptin and OB-RGRP. Amplification efficiencies calculated using Efficiency = ((10∧–1/slope)–1) [27]. (TIF)
Data
Standard curves for qPCR analysis of 18S (A), Uxt (B), Rs9 (C) and Rs15 (D). All linear regressions showed R2 values ranging from 0.9071-0.9915 and amplification efficiencies were calculated using Efficiency = ((10∧–1/slope)–1) [27]. (TIF)
Data
Standard curves for plasmid precipitation tests of leptin and OB-RGRP. Linear regression lines illustrate differences in threshold cycles (Ct) between linear and circular plasmid standards for both leptin and OB-RGRP. Amplification efficiencies calculated using Efficiency = ((10∧–1/slope)–1) [27]. (TIF)
Article
Full-text available
Paleontology provides information about the history of morphological transformations, whereas developmental biology provides information about how such transformations happen at a mechanistic level. As such, developmental evidence enriches paleontology in formulating and assessing hypotheses of homology, character definition, and character independ...
Article
Odontocetes and mysticetes are two extant suborders of cetaceans. It is reported that the former have no sense of olfaction, while the latter can smell in air. To explain the ecological reason why mysticetes still retain their sense of smell, two hypotheses have been proposed - the echolocation-priority hypothesis, which assumes that the acquisitio...
Article
Raoellids are small, raccoon-sized Eocene artiodactyls, closely related to archaic cetaceans (archaeocetes) that have poor representation of postcranial elements in the fossil record. Little is known of the aquatic and terrestrial locomotor affinities of raoellids due to the paucity of their fossil record, leaving a critical gap in our understandin...
Article
We describe the bony and cartilaginous structures of five fetal skulls of Stenella attenuata (pantropical spotted dolphin) specimens. The specimens represent early fetal life as suggested by the presence of rostral tactile hairs and the beginnings of skin pigmentation. These specimens exhibit the developmental order of ossification of the intramemb...