CRANIAL ANATOMY OF MIDDLE EOCENE REMINGTONOCETUS (CETACEA, MAMMALIA) FROM KUTCH, INDIA
hearing; Paleontology; evolution; origin; whales; transition
The family Remingtonocetidae is a basal family of Eocene cetaceans only known from near shore marine environments of India and Pakistan. We describe a new skull for Remingtonocetus harudiensis which elucidates the anatomy and functional morphology of the head and provides new details on cranial cavity and nasopharyngeal region. We suggest that Remingtonocetus was an ambush predator that hunted from a perch on the ocean floor, and that hearing was its most important sense. We speculate that the greatly elongated rostrum is an adaptation for water retention because these are some of the earliest whales living in seawater.
Bajpai S; Thewissen J G M; Conley R W
Journal of Paleontology
2011
2011-07
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1666/10-128.1" target="_blank" rel="noreferrer noopener">10.1666/10-128.1</a>
The origin and early evolution of whales: macroevolution documented on the Indian Subcontinent
Cetacea; India; evolution; energetics; Life Sciences & Biomedicine - Other Topics; artiodactyls; Eocene; pakistan; whales; cetaceans; Eocene; cetartiodactyla; locomotor evolution; dolphins; middle; semiaquatic mammals; underwater hearing
The origin of whales (order Cetacea) from a four-footed land animal is one of the best understood examples of macroevolutionary change. This evolutionary transition has been substantially elucidated by fossil finds from the Indian subcontinent in the past decade and a half. Here, we review the first steps of whale evolution, i.e. the transition from a land mammal to obligate marine predators, documented by the Eocene cetacean families of the Indian subcontinent: Pakicetidae, Ambulocetidae, Remingtonocetidae, Protocetidae, and Basilosauridae, as well as their artiodactyl sister group, the Raoellidae. We also discuss the influence that the excellent fossil record has on the study of the evolution of organ systems, in particular the locomotor and hearing systems.
Bajpai S; Thewissen J G M; Sahni A
Journal of Biosciences
2009
2009-11
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1007/s12038-009-0060-0" target="_blank" rel="noreferrer noopener">10.1007/s12038-009-0060-0</a>
Limb Preference in Animals: New Insights into the Evolution of Manual Laterality in Hominids.
Until the 1990s, the notion of brain lateralization—the division of labor between the two hemispheres—and its more visible behavioral manifestation, handedness, remained fiercely defined as a human specific trait. Since then, many studies have evidenced lateralized functions in a wide range of species, including both vertebrates and invertebrates. In this review, we highlight the great contribution of comparative research to the understanding of human handedness' evolutionary and developmental pathways, by distinguishing animal forelimb asymmetries for functionally different actions—i.e., potentially depending on different hemispheric specializations. Firstly, lateralization for the manipulation of inanimate objects has been associated with genetic and ontogenetic factors, with specific brain regions' activity, and with morphological limb specializations. These could have emerged under selective pressures notably related to the animal locomotion and social styles. Secondly, lateralization for actions directed to living targets (to self or conspecifics) seems to be in relationship with the brain lateralization for emotion processing. Thirdly, findings on primates' hand preferences for communicative gestures accounts for a link between gestural laterality and a left-hemispheric specialization for intentional communication and language. Throughout this review, we highlight the value of functional neuroimaging and developmental approaches to shed light on the mechanisms underlying human handedness.
Boulinguez-Ambroise, Grégoire
Aychet, Juliette
Pouydebat, Emmanuelle
Symmetry (20738994). Jan2022, Vol. 14 Issue 1, p96-96. 1p.
2022
English
The Trouble With Flippers: A Report On The Prevalence Of Digital Anomalies In Cetacea
abnormalities; bottle-nosed-dolphin; evolution; flipper; forelimb; hyperphalangy; limb; limb malformations; manus; mechanobiology; patterns; polydactyly; polyphalangy; tursiops-truncatus; vertebrate; Zoology
Cooper L N; Dawson S D
Zoological Journal of the Linnean Society
2009
2009-03
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1111/j.1096-3642.2008.00454.x" target="_blank" rel="noreferrer noopener">10.1111/j.1096-3642.2008.00454.x</a>
New Applications For Constrained Ordination: Reconstructing Feeding Behaviors In Fossil Remingtonocetinae (cetacea: Mammalia)
Archaeocetes; components; Constrained ordination; Eocene; eocene cetaceans; evolution; Feeding; india; Mastication; morphology; odontoceti; Reconstruction; regression; suction; transition; whales
Cooper L N; Hieronymus T L; Vinyard C J; Bajpai S; Thewissen J G M
Experimental Approaches to Understanding Fossil Organisms: Lessons from the Living
2014
1905-07
Book Chapter
n/a
Postcranial Morphology And Locomotion Of The Eocene Raoellid Indohyus (artiodactyla: Mammalia)
Artiodactyla; bone-density; Cetacea; cetartiodactyla; earliest cetaceans; early whales; evolution; fur seals; india; Indohyus; Life Sciences & Biomedicine - Other Topics; origin; osteosclerosis; pakistan; Paleontology; postcrania; Raoellidae; sea lions
Cooper L N; Thewissen J G M; Bajpai S; Tiwari B N
Historical Biology
2012
1905-07
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1080/08912963.2011.624184" target="_blank" rel="noreferrer noopener">10.1080/08912963.2011.624184</a>
New Middle Eocene Archaeocetes (cetacea:mammalia) From The Kuldana Formation Of Northern Pakistan
artiodactyls; cetaceans; early whales; evolution; locomotion; mammalia; origin; Paleontology; time; transition
Cooper L N; Thewissen J G M; Hussain S T
Journal of Vertebrate Paleontology
2009
2009-12
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1671/039.029.0423" target="_blank" rel="noreferrer noopener">10.1671/039.029.0423</a>
Brainstem Neurons With Descending Projections To The Spinal Cord Of Two Elasmobranch Fishes: Thornback Guitarfish, Platyrhinoidis Triseriata, And Horn Shark, Heterodontus Francisci
cartilaginous fish; central-nervous-system; clearnose skate; dogfish scyliorhinus-canicula; enkephalin; evolution; gigantocellular tegmental field; horseradish-peroxidase method; immunoreactive cells; medullary reticular-formation; Neurosciences & Neurology; north-american opossum; reticular formation; reticulospinal; supraspinal; tyrosine-hydroxylase; Zoology
Cruce W L R; Stuesse S L; Northcutt R G
Journal of Comparative Neurology
1999
1999-01
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/(sici)1096-9861(19990125)403:4%3C534::aid-cne8%3E3.0.co;2-8" target="_blank" rel="noreferrer noopener">10.1002/(sici)1096-9861(19990125)403:4%3C534::aid-cne8%3E3.0.co;2-8</a>
Sacroiliac joint bridging: Demographical and anatomical aspects
osteoarthritis; Orthopedics; Neurosciences & Neurology; evolution; population; idiopathic skeletal hyperostosis; sacroiliac joint; spine; ankylosing; bridging; spine diseases; spondylitis; spondyloathropathy
Study Design. A descriptive study of the association between sacroiliac joint bridging ( SIB) and age, gender, laterality, and ethnic origin in a normal skeletal population. The effectiveness of radiographs in identifying SIB was also evaluated. Objectives. To characterize the phenomenon of SIB demographically and anatomically and to evaluate the validity of diagnosis based on roentgenograms. Summary and Background Data. Although SIB is an important diagnostic parameter in many spinal diseases, the type of association between them has never been established. Furthermore, the extent of SIB in humans and its relationship to demographic parameters await osteological research as radiograph studies hamper the results. Methods. Two thousand eight hundred and forty-five skeleton pelves were examined for SIB. Extent and laterality were recorded. Ten pelves ( 5 with SIB and 5 without) were X-rayed and the roentgenograms given to radiologists for evaluation. Results. Sacroiliac bridging was present in 12.27% of all males, contrasted with only 1.83% of females ( P < 0.001). SIB was independent of ethnic origin ( P = 0.0535) but was age-dependent ( r = 0.985; P = 0.0001). Bridging was present bilaterally in 38.6% of the individuals and in the superior region in 72.4%. Diffuse bridging ( areas 1 - 6) was present in only 2.3% of the individuals. Radiologic examination was insensitive to diagnosis of SIB. Conclusions. SIB is a common, but predominantly male phenomenon. Its occurrence is age-dependent and ethnicity independent. Bridging occurs mainly on the superior aspect of the sacroiliac joint. The irregular shape and orientation of sacroiliac joints preclude definitely distinguishing normal versus bridged joints from roentgenograms. Our findings also negate the belief that bridging/ fusion of the sacroiliac joint represents the most severe form of osteoarthritis and mandate that they be separately recorded and that their significance be determined.
Dar G; Peleg S; Masharawi Y; Steinberg N; Rothschild B M; Peled N; Hershkovitz I
Spine
2005
2005-08
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1097/01.brs.0000172232.32082.e0" target="_blank" rel="noreferrer noopener">10.1097/01.brs.0000172232.32082.e0</a>
The Effect Of Food Hardness On Feeding Behaviour In Frugivorous Bats (phyllostomidae): An Experimental Study
behaviour; evolution; Feeding; fruit; fruit bats; fruit texture; modern carnivores; morphology; patterns; skull shape; strain; Zoology; zygomatic arch
Dumont E R
Journal of Zoology
1999
1999-06
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1017/s0952836999006093" target="_blank" rel="noreferrer noopener">10.1017/s0952836999006093</a>
To 3d Or Not To 3d, That Is The Question: Do 3d Surface Analyses Improve The Ecomorphological Power Of The Distal Femur In Placental Mammals?
anatomy; behavior; carnivorans; corpus; discriminant function-analysis; evolution; functional-morphology; hindlimb; locomotor; ratios; rodents; Science & Technology - Other Topics
Improvements in three-dimensional imaging technologies have renewed interest in the study of functional and ecological morphology. Quantitative approaches to shape analysis are used increasingly to study form-function relationships. These methods are computationally intensive, technically demanding, and time-consuming, which may limit sampling potential. There have been few side-by-side comparisons of the effectiveness of such approaches relative to more traditional analyses using linear measurements and ratios. Morphological variation in the distal femur of mammals has been shown to reflect differences in locomotor modes across clades. Thus I tested whether a geometric morphometric analysis of surface shape was superior to a multivariate analysis of ratios for describing ecomorphological patterns in distal femoral variation. A sample of 164 mammalian specimens from 44 genera was assembled. Each genus was assigned to one of six locomotor categories. The same hypotheses were tested using two methods. Six linear measurements of the distal femur were taken with calipers, from which four ratios were calculated. A 3D model was generated with a laser scanner, and analyzed using three dimensional geometric morphometrics. Locomotor category significantly predicted variation in distal femoral morphology in both analyses. Effect size was larger in the geometric morphometric analysis than in the analysis of ratios. Ordination reveals a similar pattern with arboreal and cursorial taxa as extremes on a continuum of morphologies in both analyses. Discriminant functions calculated from the geometric morphometric analysis were more accurate than those calculated from ratios. Both analysis of ratios and geometric morphometric surface analysis reveal similar, biologically meaningful relationships between distal femoral shape and locomotor mode. The functional signal from the morphology is slightly higher in the geometric morphometric analysis. The practical costs of conducting these sorts of analyses should be weighed against potentially slight increases in power when designing protocols for ecomorphological studies.
Gould F D H
Plos One
2014
2014-03
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1371/journal.pone.0091719" target="_blank" rel="noreferrer noopener">10.1371/journal.pone.0091719</a>
The Facial Integument Of Centrosaurine Ceratopsids: Morphological And Histological Correlates Of Novel Skin Structures
adaptation; Anatomy & Morphology; bovidae; Centrosaurinae; dinosaurs; discrete characters; evolution; horn; molecular phylogeny; ontogeny; Ovibos; Pachyrhinosaurus; papillary horn; selection; sexual selection; social; triceratops
The horned dinosaur Pachyhinosaurus possesses rugose bony bosses across the skull roof in lieu of the projecting bony horn cores seen in most ceratopsians. This elaboration of typical ceratopsian ornaments provides an opportunity to test hypotheses of ceratopsian facial skin morphology and function. We analyze bone morphology and histology associated with several classes of skin features in extant amniotes using a classification tree analysis. We isolate key osteological and histological correlates for unpreserved skin structures, including both a pattern of pitting and resorption characteristic of muskox (Ovibos) frontal horn boss, and a pattern of metaplastic ossification characteristic of rhinoceros nasal horn boss. We also describe correlates for other skin features, such as epidermal scales and horn sheaths. Dermatocranial elements from centrosaurine ceratopsians are then examined for the same osteological and histological correlates. From this comparison we propose that the rugose bosses that replace horn cores in many centrosaurine dinosaurs, most notably Achelousaurus and Pachyrhinosaurus, were covered by a thick pad of cornified skin derived from the caudodorsal side of the primitive horn sheath comparable to the horny boss of extant muskoxen (Ovibos). We examine extant taxa with skin morphologies similar to Pachyrhinosaurus for consistent adaptive relationships between structure and behavior. We determine that high-energy head-butting is consistently associated with the acquisition of thick cornified pads, seen in muskoxen as well as helmeted hornbills [Buceros (=Rhinoplax) vigil] and African buffalo (Syncerus). The association of the bony ornaments of Pachyrhinosaurus with risky agonistic behaviors casts doubt on the role of species recognition as a primary selection pressure driving the diversity of all ceratopsian horns. We conclude that social selection (a broad form of intraspecific competition) is a more appropriate explanation for the diversity of centrosaurine ceratopsian ornaments in the Late Cretaceous. Anat Rec, 292:1370-1396, 2009. (C) 2009 Wiley-Liss, Inc.
Hieronymus T L; Witmer L M; Tanke D H; Currie P J
Anatomical Record-Advances in Integrative Anatomy and Evolutionary Biology
2009
2009-09
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/ar.20985" target="_blank" rel="noreferrer noopener">10.1002/ar.20985</a>
The Anterior Dentition Of Sivapithecus-parvada, With Comments On The Phylogenetic Significance Of Incisor Heteromorphy In Hominoidea
Anthropology; clade; dentition; east-africa; evolution; Evolutionary Biology; hominids; hominoid phylogenetics; incisors; kenya; middle miocene; miocene hominoid; orangutan; origin; pakistan; pongo; sivapithecus; specimens
A premaxillary fragment of Sivapithecus parvada preserving the germs of the right central and lateral incisors is described. The specimen was recovered in situ during excavation at locality Y311 in the upper Nagri Formation (ca. 9.2 m.y.a.) of the Siwalik Sequence, Potwar Plateau, Pakistan. The central incisor is approximately 35% larger than the next largest Sivapithecus incisor, in keeping with the very large size of S. parvada compared to other Sivapithecus species, and is exceptionally long mesiodistally in relation to its breadth. It is also morphologically distinct, having a sharply angled distal margin and a distinct lingual tubercle. However, previous descriptions of Sivapithecus upper central incisors as having a continuous lingual shelf are in some cases erroneous and ignore the morphological variation present in the sample. In several features of anterior tooth size, morphology and proportionality, S. parvada resembles Pongo more than do other species of Sivapithecus. The I1/I2 length ratio of the new specimen is 2.12, the largest size disparity reported for any fossil catarrhine, and greater than any single value in a large sample of Pongo pygmaeus. Very great size disparity between upper central and lateral incisors is widely considered to be a synapomorphy of the orang-utan lineage. We conclude, however, that descriptions of upper incisor size heteromorphy in Pongo have in general been exaggerated and have failed to recognize substantial differences in this character between Bornean and Sumatran orang-utans. We further conclude, based on examination of a variety of Miocene hominoids and other Miocene catarrhine primates, that the character of I1/I2 proportionality has little if any phylogenetic utility within Hominoidea.
Kelley J; Anwar M; McCollum M A; Ward S C
Journal of Human Evolution
1995
1995-06
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1006/jhev.1995.1039" target="_blank" rel="noreferrer noopener">10.1006/jhev.1995.1039</a>
Dental Remains Of Equatorius Africanus From Kipsaramon, Tugen Hills, Baringo District, Kenya
Anthropology; baringo; dentition; Equatorius; evolution; Evolutionary Biology; hominoid genus; hominoids; kenyapithecus; Kipsaramon; middle miocene; Miocene; Muruyur; pasalar; sexual dimorphism; western kenya
Forty-one isolated large hominoid teeth, as well as most of the mandibular and three maxillary teeth associated with a partial skeleton, were recovered from middle Miocene Muruyur sediments near Kipsaramon in the Tugen Hills, Baringo District, Kenya. The isolated teeth were collected as surface finds and the skeleton was excavated in situ at locality BPRP#122 dated between 15(.)58 Ma and 15(.)36 Ma. The majority of the teeth recovered at BPRP#122 are referable to a minimum of five individuals of the hominoid Equatorius africanus. Three of the teeth, however, are provisionally assigned to Nyanzapithecus sp. The new hominoids from Kipsaramon add to an increasing inventory of specimens that suggest greater large hominoid taxonomic diversity from the middle Miocene of Kenya than was previously recognized. It is suggested that there are two large-bodied hominoid species present at Mabako, only one of which is assignable to Equatorius. (C) 2002 Academic Press.
Kelley J; Ward S; Brown B; Hill A; Duren D L
Journal of Human Evolution
2002
2002-01
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1006/jhev.2001.0504" target="_blank" rel="noreferrer noopener">10.1006/jhev.2001.0504</a>
A New Reconstruction Of Multituberculate Endocranial Casts And Encephalization Quotient Of Kryptobaatar
body mass; body-weight; brain; brain structure; cistern; encephalization quotient; endocasts; evolution; Kryptobaatar; Late Cretaceous; mammals; Mongolia; multituberculata; Paleontology; phylogeny; size; superior; tooth
Multituberculate and eutriconodontan endocasts differ from those of primitive therian mammals in their lack of visible midbrain exposure oil the dorsal side and in having a vermis-like triangular bulge (recognized herein as the cast of a large sinus-the superior cistern) inserted between the cerebral hemispheres. As the shape and proportions of multituberculate. eutriconodontan, and Cretaceous eutherian endocasts are otherwise similar, one might speculate that the multituberculate and eutriconodontan brains did not differ essentially from those of primitive eutherian and marsupial mammals, in which the midbrain is exposed dorsally. This conclusion might have important phylogenetic implications, as multituberculates and eutriconodontans may lay closer to the therians sensu strico, than hitherto believed. We describe an endocast of the Late Cretaceous multi tuberculate Kryptobaatar, which differs from those of other multituberculates (Ptilodus, Chulsan-baatar. and Nemegtbaatar) in having unusually long olfactory bulbs and the paraflocculi elongated transversely, rather than ball-shaped. We estimate the encephalization quotient (EQ) of Kryptobaatar, using: 1) Jerison's classical equation (1) based on estimation of endocranial volume and body mass-, 2) McDermott et al.'s derived body mass estimation equation (2) using upper molar lengths; and 3) estimation of body mass based on new equations (3a, 3b, 3c, and 3d(1-9)), which we propose, using measurements of the humerus, radius, ulna, femur and tibia. In both Jerison's method and a mean of out series of derived formulae, the EQ varies around 0.71, which is higher than estimated for other multituberculate mammals. It remains an open question whether the evolutionary success of Kryptobaatar (which was a dominant mammal during the ?early Campanian on the Gobi Desert and survived until the ?late Campanian) might have been related to its relatively high EQ and well developed sensorimotor adaptations, in particular olfaction and coordinated movements.
Kielan-Jaworowska Z; Lancaster T
Acta Palaeontologica Polonica
2004
2004-04
Journal Article or Conference Abstract Publication
n/a
Mycobacterium Tuberculosis Complex Lipid Virulence Factors Preserved In The 17,000-year-old Skeleton Of An Extinct Bison, Bison Antiquus
acquired genomic islands; dna; evolution; homo-erectus; Science & Technology - Other Topics; trehalose
Tracing the evolution of ancient diseases depends on the availability and accessibility of suitable biomarkers in archaeological specimens. DNA is potentially information-rich but it depends on a favourable environment for preservation. In the case of the major mycobacterial pathogens, Mycobacterium tuberculosis and Mycobacterium leprae, robust lipid biomarkers are established as alternatives or complements to DNA analyses. A DNA report, a decade ago, suggested that a 17,000-year-old skeleton of extinct Bison antiquus, from Natural Trap Cave, Wyoming, was the oldest known case of tuberculosis. In the current study, key mycobacterial lipid virulence factor biomarkers were detected in the same two samples from this bison. Fluorescence high-performance liquid chromatography (HPLC) indicated the presence of mycolic acids of the mycobacterial type, but they were degraded and could not be precisely correlated with tuberculosis. However, pristine profiles of C-29, C-30 and C-32 mycocerosates and C-27 mycolipenates, typical of the Mycobacterium tuberculosis complex, were recorded by negative ion chemical ionization gas chromatography mass spectrometry of pentafluorobenzyl ester derivatives. These findings were supported by the detection of C-34 and C-36 phthiocerols, which are usually esterified to the mycocerosates. The existence of Pleistocene tuberculosis in the Americas is confirmed and there are many even older animal bones with well-characterised tuberculous lesions similar to those on the analysed sample. In the absence of any evidence of tuberculosis in human skeletons older than 9,000 years BP, the hypothesis that this disease evolved as a zoonosis, before transfer to humans, is given detailed consideration and discussion.
Lee O Y C; Wu H H T; Donoghue H D; Spigelman M; Greenblatt C L; Bull I D; Rothschild B M; Martin L D; Minnikin D E; Besra G S
Plos One
2012
2012-07
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1371/journal.pone.0041923" target="_blank" rel="noreferrer noopener">10.1371/journal.pone.0041923</a>
Morphological Correlates Of Substrate Use In Didelphid Marsupials: Implications For Primate Origins
behavior; cercopithecidae; cheirogaleid primates; didelphid marsupials; evolution; foot; forest; french-guyana; hand; locomotion; mass; opossum caluromys-philander; posture; prehensility; small mammals; Zoology
The ability of some mammals to forage on vines or terminal branches depends upon their grasping extremities. This study tests the functional link between use of small-diameter supports and grasping abilities by comparing hand and foot proportions in didelphid marsupials. Metapodials and phalanges were measured for the hands and feet of six didelphid taxa characterized by different patterns of substrate use. Comparisons of hand and foot proportions demonstrate that Marmosa and Caluromys, didelphids that rely on vines or terminal branches, possess more prehensile extremities than Monodelphis, Didelphis, and Philander, which travel and feed mainly on the ground. Moreover, the proportions of the hand and foot of Marmosa and Caluromys are more similar to those of cheirogaelid primates than those of other didelphids. These morphological data corroborate the suggestion that the use of branches of small diameter was an important factor in the development of prehensile hands and feet in early primates.
Lemelin P
Journal of Zoology
1999
1999-02
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1017/s0952836999002046" target="_blank" rel="noreferrer noopener">10.1017/s0952836999002046</a>
Comparative embryology of Delphinapterus leucas (beluga whale), Balaena mysticetus (bowhead whale), and Stenella attenuata (pan-tropical spotted dolphin) (Cetacea: Mammalia)
Embryogenesis of cetaceans (whales, dolphins, porpoises) is best known in Stenella attenuata, the pan-tropical spotted dolphin, based on a remarkably complete and well-studied prenatal ontogenetic series. Our study expands understanding of cetacean embryology by adding two additional cetacean taxa: the beluga whale (Delphinapterus leucas, Odontoceti), and the bowhead whale (Balaena mysticetus, Mysticeti). We identify key features that characterize these taxa at specific stages and highlight heterochrony between the odontocetes and mysticetes. The toothed whales are more similar in developmental timing to each other than either is to Balaena. The two odontocete taxa, Stenella and Delphinapterus, share similar developmental trajectories while early Balaena specimens differ from the odontocetes. This developmental variation proves challenging to ascribe to the existing Carnegie staging system. Most notably, flippers, hindlimbs, and flukes all provide morphological traits for characterization within the Carnegie staging system. A presomitic Delphinapterus embryo is also described. This study applies the Carnegie staging system to two more cetacean taxa and forms a framework for future research on cetacean developmental genetics and the modeling of fetal growth.
Lia Gavazzi
Lisa N Cooper
Sharon Usip
Robert Suydam
Raphaela Stimmelmayr
John C George
Greg O'Corry-Crowe
Chih-Wei Hsu
Johannes Thewissen
J Morphol
. 2023 Feb;284(2):e21543. doi: 10.1002/jmor.21543.
2023
English
Built To Last: The Structure, Function, And Evolution Of Primate Dental Enamel
Anthropology; dental function; diet; enamel microstructure; enamel prisms; evolution; expression patterns; hard tissues; homeobox gene; human-teeth; incremental markings; microstructure; microwear; primate; primate phylogeny; thickness; tooth enamel
Maas M C; Dumont E R
Evolutionary Anthropology
1999
1999
Journal Article or Conference Abstract Publication
n/a
Enigmatic New Ungulates From The Early Middle Eocene Of Central Anatolia, Turkey
basin; evolution; mammalia; oligocene; osteology; pakistan; Paleontology; position
Maas M C; Thewissen J G M; Sen S; Kazanci N; Kappelman J
Journal of Vertebrate Paleontology
2001
2001-08
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1671/0272-4634(2001)021%5B0578:enufte%5D2.0.co;2" target="_blank" rel="noreferrer noopener">10.1671/0272-4634(2001)021%5B0578:enufte%5D2.0.co;2</a>
Additional Holotype Remains Of Ambulocetus Natans (cetacea, Ambulocetidae), And Their Implications For Locomotion In Early Whales
earliest cetaceans; Eocene; evolution; extant taxa; extinct; mammalia; morphology; origin; osteology; Paleontology; skeleton
Madar S I; Thewissen J G M; Hussain S T
Journal of Vertebrate Paleontology
2002
2002-07
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1671/0272-4634(2002)022%5B0405:ahroan%5D2.0.co;2" target="_blank" rel="noreferrer noopener">10.1671/0272-4634(2002)022%5B0405:ahroan%5D2.0.co;2</a>
Subnasoalveolar anatomy and hominoid phylogeny: Evidence from comparative ontogeny
Anthropology; Evolutionary Biology; evolution; allometry; great apes; miocene; form; sexual dimorphism; extant; fossil hominids; Homo; late; african apes; facial kyphosis; character phylogeny; chimp; hylobatids; ontogenetic; orangutans; skull material; subnasal development
The present analysis evaluated extant hominoid subnasal morphological variation from an ontogenetic perspective, documenting both qualitative and allometric details of subnasal maturation in Hylobates, great apes and modern humans. With respect to intraspecific variation, results of log-linear modeling procedures indicate that qualitative features of the subnasal region shown previously to discriminate extant taxa (Ward and Kimbel, 1983; McCollum et al., 1993) do not vary appreciably with either age or sex. In terms of quantitative variation, aside from observed changes in the position of the anterior attachment of the nasal septal cartilage relative to the lateral margins of the nasal cavity, the morphology of the subnasal region does not vary appreciably with age. Furthermore, it was found that sexual dimorphism in subnasal form is present only in Pongo and Gorilla and is the result of sexual bimaturism rather than sexual variation in canine size. In considering interspecific variation in subnasal form, there is a propensity among hominoid taxa for the nasal cavity floor to be free of substantial topographic relief. The smoothly continuous nasal floor topography identified in the majority of hominoid taxa appears to be produced by extensive resorption of the anterior nasal cavity floor that accompanies an upward rotation of the anterior maxilla during craniofacial ontogeny. Comparisons of ontogenetic allometric trajectories indicate that relatively little of the variation in hominoid subnasal form can easily be attributed to variation in body/cranial size. Instead, variation in craniofacial orientation, vascular anatomy and incisor size and inclination were identified as potential mediators of hominoid subnasoalveolar anatomy. Although results of this analysis confirm that many details of the orangutan subnasal morphology are derived for this taxon, there is little conclusive evidence to support recent reports that the morphology displayed by Gorilla is primitive for great apes (Begun, 1992, 1994). (C) 1997 Wiley-Liss, Inc.
McCollum M A; Ward S C
American Journal of Physical Anthropology
1997
1997-03
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/(sici)1096-8644(199703)102:3%3C377::aid-ajpa7%3E3.0.co;2-s" target="_blank" rel="noreferrer noopener">10.1002/(sici)1096-8644(199703)102:3%3C377::aid-ajpa7%3E3.0.co;2-s</a>
Morphometry, Geometry, Function, and the Future
Anatomy & Morphology; evolution; morphology; performance; primates; darwins finches; adaptation; selection; form; evolutionary; fitness; shape; biological anthropology; geometric morphometrics
The proliferation of geometric morphometrics (GM) in biological anthropology and more broadly throughout the biological sciences has resulted in a multitude of studies that adopt landmark-based approaches for addressing a variety of questions in evolutionary morphology. In some cases, particularly in the realm of systematics, the fit between research question and analytical design is quite good. Functional-adaptive studies, however, do not readily conform to the methods available in the GM toolkit. The symposium organized by Terhune and Cooke entitled Assessing function via shape: What is the place of GM in functional morphology? held at the 2013 meetings of the American Association of Physical Anthropologists was designed specifically to explore this relationship between landmark-based methods and analyses of functional morphology, and the articles in this special issue, which stem in large part from this symposium, provide numerous examples of how the two approaches can complement and contrast each other. Here, we underscore some of the major difficulties in interpreting GM results within a functional regime. In combination with other contributions in this issue, we identify emerging areas of research that will help bridge the gap between multivariate morphometry and functional-adaptive analysis. Ultimately, neither geometric nor functional morphometric approaches is sufficient to elaborate the adaptive pathways that explain morphological evolution through natural selection. These perspectives must be further integrated with research from physiology, developmental biology, genomics, and ecology. Anat Rec, 298:328-333, 2015. (c) 2014 Wiley Periodicals, Inc.
McNulty K P; Vinyard C J
Anatomical Record-Advances in Integrative Anatomy and Evolutionary Biology
2015
2015-01
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/ar.23064" target="_blank" rel="noreferrer noopener">10.1002/ar.23064</a>
An experimental analysis of feeding performance in Syconycteris australis (Megachiroptera, Pteropodidae)
blossom-bat; chiroptera; energetics; evolution; Feeding; flower shape; mammalia; morphology; nectar; phylogeny; pollen; Syconycteris; Zoology
The hypothesis that flower shape affects nectar-feeding performance was examined for the nectarivorous bat, Syconycteris australis. Experiments using feeders with artificial flowers of different diameters demonstrated that the narrow flower diameter had a negative effect on time spent feeding, amount of nectar taken, and rate of nectar extraction. These results suggest that flower morphology may influence both evolution of the masticatory system and resource partitioning by affecting feeding performance in flower-visiting bats.
Nicolay C W; Dumont E R
Mammalia
2000
2000
Journal Article
<a href="http://doi.org/10.1515/mamm.2000.64.2.155" target="_blank" rel="noreferrer noopener">10.1515/mamm.2000.64.2.155</a>
A retroposon analysis of Afrotherian phylogeny
Afrotheria; base composition; Biochemistry & Molecular Biology; elements; endemic african mammals; evolution; Evolutionary Biology; Genes; Genetics &; Heredity; mammalian phylogeny; mitochondrial genomes; molecular evidence; Paenungulata; placental mammals; retroposons; SINEs; SINEs; support; Tethytheria
Recent comprehensive studies of DNA sequences support the monophyly of Afrotheria, comprising elephants, sirenians (dugongs and manatees), hyraxes, tenrecs, golden moles, aardvarks, and elephant shrews, as well as that of Paenungulata, comprising elephants, sirenians, and hyraxes. However, phylogenetic relationships among paenungulates, as well as among nonpaenungulates, have remained ambiguous. Here we applied an extensive retroposon analysis to these problems to support the monophyly of aardvarks, tenrecs, and golden moles, with elephant shrews as their sister group. Regarding phylogenetic relationships in Paenungulata, we could characterize only one informative locus, although we could isolate many insertions specific to each of three lineages, namely, Proboscidea, Sirenia, and Hyracoidea. These data prompted us to reexamine phylogenetic relationships among Paenungulata using 19 nuclear gene sequences resulting in three different analyses, namely, short interspersed element (SINE) insertions, nuclear sequence analyses, and morphological cladistics, supporting different respective phylogenies. We concluded that these three lineages diverged very rapidly in a very short evolutionary period, with the consequence that ancestral polymorphism present in the last common ancestor of Paenungulata results in such incongruence. Our results suggest the rapid fixation of many large-scale morphological synapomorphies for Tethytheria; implications of this in relation to the morphological evolution in Paenungulata are discussed.
Nishihara H; Satta Y; Nikaido M; Thewissen J G M; Stanhope M J; Okada N
Molecular Biology and Evolution
2005
2005-09
Journal Article
<a href="http://doi.org/10.1093/molbev/msi179" target="_blank" rel="noreferrer noopener">10.1093/molbev/msi179</a>
Cranial anatomy of Pakicetidae (Cetacea, Mammalia)
artiodactyls; eocene; evolution; hearing; origin; pakistan; Paleontology; whales
The skulls and isolated tympanics are described for the earliest whales, pakicetids, from the H-GSP Locality 62 in the Ganda Kas area in Northern Pakistan. Currently three pakicetid genera are known: Pakicetus, Ichthyolestes, and Nalacetus. Ichthyolestes is smaller than the two other genera. Nalacetus and Pakicetus are similar in size, but morphologically different. Pakicetids have a nasal opening at the tip of the rostrum. Their palate retains an incisive foramen. This study reveals three characters of the cranial anatomy useful for systematic analyses. In pakicetids the orbits are orientated dorsally, and there is no supraorbital shield. The dorsal orientation of the orbits is diagnostic for the family, and the lack of supraorbital shield distinguishes pakicetids, ambulocetids, and remingtonocetids from the other Eocene archaeocetes. The intertemporal region of the pakicetid skull is very narrow, a feature that also occurs in many other Eocene cetaceans. The tympanic, which is the most abundant cranial bone (more than 30 specimens) in the pakicetid collections from H-GSP Locality 62, can be used to distinguish the species of pakicetids. In Ichthyolestes, the tympanic bulla is of the same absolute size as in Pakicetus, hence relatively larger, and the tympanic bulla of Nalacetus is larger than either of these. Morphologically, the tympanic bullae differ between the genera, and on the basis of these morphologies it is possible to recognize a fourth species of pakicetid at this locality.
Nummela S; Hussain S T; Thewissen J G M
Journal of Vertebrate Paleontology
2006
2006-09
Journal Article
<a href="http://doi.org/10.1671/0272-4634(2006)26%5B746:caopcm%5D2.0.co;2" target="_blank" rel="noreferrer noopener">10.1671/0272-4634(2006)26%5B746:caopcm%5D2.0.co;2</a>
Scaling of the marsupial middle ear and its functional significance
absolute; allometry; auditory characteristics; evolution; hearing; hearing sensitivity; impedance; mammal; marsupial; middle ear; mongolian gerbil; monodelphis-domestica; primitive mammals; pure-tone thresholds; size; trichosurus-vulpecula; Zoology
The marsupial middle ear performs an anatomical impedance matching for acoustic energy travelling in air to reach the cochlea. The size of the middle ear sets constraints for the frequencies transmitted. For generalized placental mammals, it has been shown that the limit for high-frequency hearing can be predicted on the basis of middle ear ossicle mass, provided that the ears fulfil requirements of isometry. We studied the interspecific size variation of the middle ear in 23 marsupial species, with the following measurable parameters: skull mass, condylobasal length, ossicular masses for malleus, incus and stapes, tympanic membrane area, oval window area, and lever arm lengths for malleus and incus. Our results show that the middle ear size grows with negative allometry in relation to body size and that the internal proportions of the marsupial middle ear are largely isometric. This resembles the situation in placental mammals and allows us to use their isometric middle ear model to predict the high-frequency hearing limit for marsupials. We found that the isometry model predicts the high-frequency hearing limit for different marsupials well, indicating that marsupials can be used as auditory models for general therian mammalian hearing. At very high frequencies, other factors, such as the inner ear, seem to constrain mammalian hearing.
Nummela S; Sanchez-Villagra M R
Journal of Zoology
2006
2006-10
Journal Article
<a href="http://doi.org/10.1111/j.1469-7998.2006.00126.x" target="_blank" rel="noreferrer noopener">10.1111/j.1469-7998.2006.00126.x</a>
Early eocene snakes from Kutch, Western India, with a review of the palaeophiidae
Boidae; Colubroidea; eocene; evolution; India; Madtsoiidae; new species; palaeoenvironment; Palaeophiidae; Paleontology; reptilia; serpentes; Ypresian
The early Eocene of Panandhro Mine (northwestern India) has produced a rich snake fauna largely dominated by palaeophiids. Three families are present: Palaeophiidae, ?Madtsoiidae or Boidae, and an indeterminate family of Colubroidea. The Palaeophiidae include two species: Pterosphenus kutchensis n. sp., that shows peculiar features, and Pt. biswasi n. sp. They are the earliest representatives of the genus. Madtsoiidae or Boidae are represented by only two specimens that do not permit distinction between these two families. If these fossils belong to the Boidae, then they might be the earliest representatives of that family in Asia. The colubroid from this site ranks among the earliest Cenozoic representatives of the group. The possibility that it belongs to n the Colubridae cannot be excluded; if this is the case, it would be the earliest known colubrid. Nearly all specimens belong to Pterosphenus Lucas, 1899, that was a highly aquatic genus. It lived in shallow water, probably in marine environment close to the coasts and/or in freshwater.
Rage J C; Bajpai S; Thewissen J G M; Tiwari B N
Geodiversitas
2003
2003
Journal Article
n/a
An analysis of von Economo neurons in the cerebral cortex of cetaceans, artiodactyls, and perissodactyls
Anatomy & Morphology; anterior cingulate cortex; bowhead whale; brain; cetartiodactyla; Cingulate; cortex; Cortical evolution; evolution; evolution; Fork cells; frontoinsular cortex; great apes; Insula; Neurosciences & Neurology; phylogeny; spindle neurons; variant frontotemporal dementia; Von Economo neurons (VENs); whale
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, macaque monkeys, elephants, and some cetaceans. Recently, a ubiquitous distribution of VENs was reported in various cortical areas in the pygmy hippopotamus, one of the closest living relatives of cetaceans. That finding suggested that VENs might not be unique to only a few species that possess enlarged brains. In the present analysis, we assessed the phylogenetic distribution of VENs within species representative of the superordinal clade that includes cetartiodactyls and perissodactyls, as well as afrotherians. In addition, the distribution of fork cells that are often found in close proximity to VENs was also assessed. Nissl-stained sections from the frontal pole, anterior cingulate cortex, anterior insula, and occipital pole of bowhead whale, cow, sheep, deer, horse, pig, rock hyrax, and human were examined using stereologic methods to quantify VENs and fork cells within layer V of all four cortical regions. VENs and fork cells were found in each of the species examined here with species-specific differences in distributions and densities. The present results demonstrated that VENs and fork cells were not restricted to highly encephalized or socially complex species, and their repeated emergence among distantly related species seems to represent convergent evolution of specialized pyramidal neurons. The widespread phylogenetic presence of VENs and fork cells indicates that these neuron morphologies readily emerged in response to selective forces,whose variety and nature are yet to be identified.
Raghanti M A; Spurlock L B; Treichler F R; Weigel S E; Stimmelmayr R; Butti C; Thewissen Jgmh; Hof P R
Brain Structure & Function
2015
2015-07
Journal Article
<a href="http://doi.org/10.1007/s00429-014-0792-y" target="_blank" rel="noreferrer noopener">10.1007/s00429-014-0792-y</a>
Ossification of the mouse metatarsal: Differentiation and proliferation in the presence/absence of a defined growth plate
Anatomy & Morphology; bone growth; cartilage fixation; cell-proliferation; chick limb buds; chondrocyte; chondrocyte proliferation; differential growth; endochondral ossification; epiphysis; evolution; hedgehog; hypertrophic differentiation; matrix proteoglycans; rat; skeletal formation
There is significant diversity in growth plate behavior among sites within an individual skeleton and between skeletons of different species. This variation within wild-type animals is an underutilized resource for studying skeletal development. One bone that potentially exhibits the most diverse behavior is the metatarsal. While one end forms a growth plate with an epiphyseal secondary center of ossification as in other long bones, the opposite end undergoes direct ossification in a manner more similar to short bones. Although descriptions of human metatarsal/metacarpal ossification are available, a detailed comparative analysis has yet to be conducted in an animal model amenable to biomolecular analysis. Here we report an analysis of proximal and distal ossification in an age series of mouse metatarsals. Safranin 0 staining was used for qualitative and quantitative histology, and chondrocyte differentiation and proliferation were analyzed using immunohistochemistry for type X collagen and proliferative cell nuclear antigen expression. We establish that, as in the human, both growth plate formation and direct ossification occur in the mouse metatarsal, with chondrocyte populations showing distinct differentiation patterns at opposite ends of the bone. In addition, growth plate formation is characterized by a peak of proliferation in reserve zone chondrocytes that distinguishes it from both established growth plates and direct ossification. Our analysis demonstrates that the mouse metatarsal is a productive model for investigating natural variation in ossification that can further understanding of vertebrate skeletal development and evolution. (C) 2005 Wiley-Liss, Inc.
Reno P L; McBurney D L; Lovejoy C O; Horton W E
Anatomical Record Part a-Discoveries in Molecular Cellular and Evolutionary Biology
2006
2006-01
Journal Article
<a href="http://doi.org/10.1002/ar.a.20268" target="_blank" rel="noreferrer noopener">10.1002/ar.a.20268</a>
Evidence from surface microscopy for recognition of fleshy and tendinous muscle insertion in extant vertebrate femora: implications for muscle reconstruction in fossils
attachment sites; bird; birds neornithes; bone-tendon; Dinosaur; entheseal changes; evolution; Life Sciences & Biomedicine - Other Topics; mammal; mechanical load; muscle; musculoskeletal stress markers; Paleontology; pelvic musculature; reptile; soft-tissues; tendon; upper-limb
Recognition of muscle attachment sites and their modification has been an important tool in anthropologic and paleontologic research, but has been compromised by limited ability to recognise sites of tendinous attachments. We investigated bone-tendon (three sites) and bone-muscle (six sites) interfaces in six pairs of femora across a broad taxonomic spectrum of higher amniote archosaurs (both recent and fossil) by epi-illumination microscopy. Direct fleshy and indirect tendinous muscle attachments were identified by dissection of fresh specimens and examination of fossils and the surface microscopic changes identified at those locations. Examination revealed bone modifications specific to each type of muscle insertion, allowing them to be identified and distinguished. Application of a surface microscopy technique not only permits more confident localisation of tendinous attachments, but for the first time allows recognition of sites of direct fleshy muscle attachments - in a reproducible manner across phylogenetic lines.
Rothschild B M; Wilhite D R; McLeod D S; Ting H
Historical Biology
2016
2016-08
Journal Article
<a href="http://doi.org/10.1080/08912963.2015.1049163" target="_blank" rel="noreferrer noopener">10.1080/08912963.2015.1049163</a>
Adaptations for marine habitat and the effect of Triassic and Jurassic predator pressure on development of decompression syndrome in ichthyosaurs
body; Caisson disease; deep; endothermy; evolution; Ichthyosaurs; oxygen; red muscle; reptiles; Science & Technology - Other Topics; swimming speed; thunnus-thynnus; Triassic; tuna katsuwonus-pelamis
Decompression syndrome (caisson disease or the "the bends") resulting in avascular necrosis has been documented in mosasaurs, sauropterygians, ichthyosaurs, and turtles from the Middle Jurassic to Late Cretaceous, but it was unclear that this disease occurred as far back as the Triassic. We have examined a large Triassic sample of ichthyosaurs and compared it with an equally large post-Triassic sample. Avascular necrosis was observed in over 15 % of Late Middle Jurassic to Cretaceous ichthyosaurs with the highest occurrence (18 %) in the Early Cretaceous, but was rare or absent in geologically older specimens. Triassic reptiles that dive were either physiologically protected, or rapid changes of their position in the water column rare and insignificant enough to prevent being recorded in the skeleton. Emergency surfacing due to a threat from an underwater predator may be the most important cause of avascular necrosis for air-breathing divers, with relative frequency of such events documented in the skeleton. Diving in the Triassic appears to have been a "leisurely" behavior until the evolution of large predators in the Late Jurassic that forced sudden depth alterations contributed to a higher occurrence of bends.
Rothschild B M; Xiaoting Z; Martin L D
Naturwissenschaften
2012
2012-06
Journal Article
<a href="http://doi.org/10.1007/s00114-012-0918-0" target="_blank" rel="noreferrer noopener">10.1007/s00114-012-0918-0</a>
Foramen magnum position in bipedal mammals
Anthropology; australopithecus-africanus; basicranial flexion; Basicranium; condyles; Convergent; cranial base; energetic cost; evolution; Evolutionary Biology; hominids; Hominin; Locomotion; occipital; Orthogrady; pliopleistocene; postnatal-development; relative brain size; sahelanthropus-tchadensis; south-africa; Trunk posture
The anterior position of the human foramen magnum is often explained as an adaptation for maintaining balance of the head atop the cervical vertebral column during bipedalism and the assumption of orthograde trunk postures. Accordingly, the relative placement of the foramen magnum on the basicranium has been used to infer bipedal locomotion and hominin status for a number of Mio-Pliocene fossil taxa. Nonetheless, previous studies have struggled to validate the functional link between foramen magnum position and bipedal locomotion. Here, we test the hypothesis that an anteriorly positioned foramen magnum is related to bipedalism through a comparison of basicranial anatomy between bipeds and quadrupeds from three mammalian clades: marsupials, rodents and primates. Additionally, we examine whether strepsirrhine primates that habitually assume orthograde trunk postures exhibit more anteriorly positioned foramina magna compared with non-orthograde strepsirrhines. Our comparative data reveal that bipedal marsupials and rodents have foramina magna that are more anteriorly located than those of quadrupedal close relatives. The foramen magnum is also situated more anteriorly in orthograde strepsirrhines than in pronograde or antipronograde strepsirrhines. Among the primates sampled, humans exhibit the most anteriorly positioned foramina magna. The results of this analysis support the utility of foramen magnum position as an indicator of bipedal locomotion in fossil hominins. (C) 2013 Elsevier Ltd. All rights reserved.
Russo G A; Kirk E C
Journal of Human Evolution
2013
2013-11
Journal Article
<a href="http://doi.org/10.1016/j.jhevol.2013.07.007" target="_blank" rel="noreferrer noopener">10.1016/j.jhevol.2013.07.007</a>
The Career Development Quarterly: A Centennial Retrospective
evolution; Psychology
The Career Development Quarterly has been the premier journal in the field of vocational guidance and career intervention since its inception 100 years ago. To celebrate its centennial, 3 former editors trace its evolution from a modest and occasional newsletter to its current status as a major professional journal. They recount its history of publishing foundational articles in vocational guidance practice and career development theory, commitment to improving counseling practice, leadership in public policy and social justice issues, and expansion to international audiences.
Savickas M L; Pope M; Niles S G
Career Development Quarterly
2011
2011-12
Journal Article
<a href="http://doi.org/10.1002/j.2161-0045.2011.tb00974.x" target="_blank" rel="noreferrer noopener">10.1002/j.2161-0045.2011.tb00974.x</a>
Human quadrupeds, primate quadrupedalism, and Uner Tan Syndrome.
Adult; Female; Humans; Male; Animals; Child; Infant; Gait/*physiology; Syndrome; *Primates; Posture/physiology; Walking/*physiology; Molecular; Evolution
Since 2005, an extensive literature documents individuals from several families afflicted with "Uner Tan Syndrome (UTS)," a condition that in its most extreme form is characterized by cerebellar hypoplasia, loss of balance and coordination, impaired cognitive abilities, and habitual quadrupedal gait on hands and feet. Some researchers have interpreted habitual use of quadrupedalism by these individuals from an evolutionary perspective, suggesting that it represents an atavistic expression of our quadrupedal primate ancestry or "devolution." In support of this idea, individuals with "UTS" are said to use diagonal sequence quadrupedalism, a type of quadrupedal gait that distinguishes primates from most other mammals. Although the use of primate-like quadrupedal gait in humans would not be sufficient to support the conclusion of evolutionary "reversal," no quantitative gait analyses were presented to support this claim. Using standard gait analysis of 518 quadrupedal strides from video sequences of individuals with "UTS", we found that these humans almost exclusively used lateral sequence-not diagonal sequence-quadrupedal gaits. The quadrupedal gait of these individuals has therefore been erroneously described as primate-like, further weakening the "devolution" hypothesis. In fact, the quadrupedalism exhibited by individuals with UTS resembles that of healthy adult humans asked to walk quadrupedally in an experimental setting. We conclude that quadrupedalism in healthy adults or those with a physical disability can be explained using biomechanical principles rather than evolutionary assumptions.
Shapiro Liza J; Cole Whitney G; Young Jesse W; Raichlen David A; Robinson Scott R; Adolph Karen E
PloS one
2014
2014
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1371/journal.pone.0101758" target="_blank" rel="noreferrer noopener">10.1371/journal.pone.0101758</a>
Preliminary description of the Equatorius africanus partial skeleton (KNM-TH 28860) from Kipsaramon, Tugen Hills, Baringo District, Kenya
Anthropology; Equatorius africanus; evolution; Evolutionary Biology; genus; hominoid; Kenya; Kipsaramon; Middle Miocene; Middle Miocene; Muruyur; phylogenetic affinities; proconsul-nyanzae; rusinga-island; site
A partial skeleton was recovered from middle Miocene Muruyur sediments near Kipsaramon in the Tugen Hills, Baringo District, Kenya. The specimen, representing much of the upper skeleton, comes from locality BPRP#122 dated between 15(.)58 Ma and 15(.)36 Ma. It is referable to the middle Miocene hominoid taxon Equatorius africanus. Preliminary descriptions of the partial skeleton are provided. While the anatomy of the wrist, thorax and hindlimb in Equatorius is similar to that of Afropithecus and Proconsul, the morphology of the new skeleton confirms earlier interpretations of greater terrestriality in Equatorius. (C) 2002 Academic Press.
Sherwood R J; Ward S; Hill A; Duren D L; Brown B; Downs W
Journal of Human Evolution
2002
2002-01
Journal Article
<a href="http://doi.org/10.1006/jhev.2001.0502" target="_blank" rel="noreferrer noopener">10.1006/jhev.2001.0502</a>
New specimens of Elphidotarsius russelli (Mammalia, ?Primates, Carpolestidae) and a revision of plesiadapoid relationships
alberta; evolution; late; ordered characters; outgroups; paleocene; Paleontology; parsimony; plesiadapiformes; primatomorpha; pronothodectes-gaoi fox; systematic position
Significant new material of the plesiadapiform Elphidotarsius russelli is described from Montana and Alberta. Previously the most poorly documented carpolestid, this species is now known from numerous isolated teeth and many jaw fragments. New material from the Crazy Mountains Basin, Montana substantially extends its known geographic range and shows that E. russelli is the most derived species of Elphidotarsius, with many features that foreshadow characteristics of Carpodaptes; consequently, emending the diagnosis of Elphidotarsius has been necessary. A phylogenetic analysis based on 73 characters scored for all species of Elphidotarsius. Pronothodectes, and Saxonella, as well as Purgatorius unio, Purgatorius janisae, Pandemonium dis, Chronolestes simul, and Carpodaptes hazelae, indicates that Elphidotarsius is a paraphyletic stem taxon at the base of Carpolestidae. Numerous crossing synapo-morphies among these taxa show that a single anagenetic lineage can no longer represent the evolution of early carpolestids. This analysis also clarifies basal plesiadapoid relationships. Carpolestidae is the sister taxon to Plesiadapidae, and Saxonellidae is sister group to the carpolestid/plesiadapid clade. Contrary to previous hypotheses, Chronolestes and Pandemonium are found to lie outside of a clade including the other members of Carpolestidae, Saxonellidae, and Plesiadapidae, implying that they are basal plesiadapoids that diverged before the evolution of the common ancestor to the three main plesiadapoid families.
Silcox M T; Krause D W; Maas M C; Fox R C
Journal of Vertebrate Paleontology
2001
2001-03
Journal Article
<a href="http://doi.org/10.1671/0272-4634(2001)021%5B0132:nsoerm%5D2.0.co;2" target="_blank" rel="noreferrer noopener">10.1671/0272-4634(2001)021%5B0132:nsoerm%5D2.0.co;2</a>
Cross Sectional Geometry of the Forelimb Skeleton and Flight Mode in Pelecaniform Birds
allometry; Anatomy & Morphology; aves; behavior; cross-sectional geometry; evolution; flight; functional-morphology; Locomotion; long bones; pelecaniforms; phylogenies; regression; size; variables
Avian wing elements have been shown to experience both dorsoventral bending and torsional loads during flapping flight. However, not all birds use continuous flapping as a primary flight strategy. The pelecaniforms exhibit extraordinary diversity in flight mode, utilizing flapping, flap-gliding, and soaring. Here we (1) characterize the cross-sectional geometry of the three main wing bone (humerus, ulna, carpometacarpus), (2) use elements of beam theory to estimate resistance to loading, and (3) examine patterns of variation in hypothesized loading resistance relative to flight and diving mode in 16 species of pelecaniform birds. Patterns emerge that are common to all species, as well as some characteristics that are flight-and diving-mode specific. In all birds examined, the distal most wing segment (carpometacarpus) is the most elliptical (relatively high I-max/I-min) at mid-shaft, suggesting a shape optimized to resist bending loads in a dorsoventral direction. As primary flight feathers attach at an oblique angle relative to the long axis of the carpometacarpus, they are likely responsible for inducing bending of this element during flight. Moreover, among flight modes examined the flapping group (cormorants) exhibits more elliptical humeri and carpometacarpi than other flight modes, perhaps pertaining to the higher frequency of bending loads in these elements. The soaring birds (pelicans and gannets) exhibit wing elements with near-circular cross-sections and higher polar moments of area than in the flap and flap-gliding birds, suggesting shapes optimized to offer increased resistance to torsional loads. This analysis of cross-sectional geometry has enhanced our interpretation of how the wing elements are being loaded and ultimately how they are being used during normal activities. J. Morphol. 272: 958-971, 2011. (C) 2011 Wiley-Liss, Inc.
Simons E L R; Hieronymus T L; O'Connor P M
Journal of Morphology
2011
2011-08
Journal Article
<a href="http://doi.org/10.1002/jmor.10963" target="_blank" rel="noreferrer noopener">10.1002/jmor.10963</a>
Palate Variation and Evolution in New World Leaf-Nosed and Old World Fruit Bats (Order Chiroptera)
cranial shape; Craniofacial; evolution; Evolutionary Biology; feeding-behavior; fluctuating asymmetry; food hardness; fossil; geometric; Integration; Modularity; Modularity; morphological integration; Morphometrics; Morphometrics; patterns; Phyllostomid; Pteropodid; record; skull morphology
Two bat families, the leaf-nosed (Phyllostomidae) and fruit bats (Pteropodidae), have independently evolved the ability to consume plant resources. However, despite their similar ages, species richness and the strong selective pressures placed on the evolution of skull shape by plant-based foods, phyllostomids display more craniofacial diversity than pteropodids. In this study, we used morphometrics to investigate the distribution of palate variation and the evolution of palate diversity in these groups. We focused on the palate because evolutionary alterations in palate morphology are thought to underlie much feeding specialization in bats. We hypothesize that the distribution of palate variation differs in phyllostomids and pteropodids, and that the rate of palate evolution is higher in phyllostomids than pteropodids. The results suggest that the overall level of palate integration is higher in adult populations of pteropodids than phyllostomids but that the distribution of palate variation is otherwise generally conserved among phyllostomids and pteropodids. Furthermore, the results are consistent with these differences in palate integration likely having a developmental basis. The results also suggest that palate evolution has occurred significantly more rapidly in phyllostomids than pteropodids. These findings are consistent with a scenario in which the greater integration of the pteropodid palate has limited its evolvability.
Sorensen D W; Butkus C; Cooper L N; Cretekos C J; Rasweiler J J; Sears K E
Evolutionary Biology
2014
2014-12
Journal Article
<a href="http://doi.org/10.1007/s11692-014-9291-6" target="_blank" rel="noreferrer noopener">10.1007/s11692-014-9291-6</a>
The Relationships Among Jaw-Muscle Fiber Architecture, Jaw Morphology, and Feeding Behavior in Extant Apes and Modern Humans
african apes; anthropoid primates; Anthropology; consequences; cross-sectional area; diet; evolution; Evolutionary Biology; finite-element-analysis; functional; hominoids; internal architecture; macaca-fascicularis; mandibular symphysis; masseter; mountain gorilla; pan-troglodytes; Temporalis
The jaw-closing muscles are responsible for generating many of the forces and movements associated with feeding. Muscle physiologic cross-sectional area (PCSA) and fiber length are two architectural parameters that heavily influence muscle function. While there have been numerous comparative studies of hominoid and hominin craniodental and mandibular morphology, little is known about hominoid jaw-muscle fiber architecture. We present novel data on masseter and temporalis internal muscle architecture for small-and large-bodied hominoids. Hominoid scaling patterns are evaluated and compared with representative New- (Cebus) and Old-World (Macaca) monkeys. Variation in hominoid jaw-muscle fiber architecture is related to both absolute size and allometry. PCSAs scale close to isometry relative to jaw length in anthropoids, but likely with positive allometry in hominoids. Thus, large-bodied apes may be capable of generating both absolutely and relatively greater muscle forces compared with smaller-bodied apes and monkeys. Compared with extant apes, modern humans exhibit a reduction in masseter PCSA relative to condyle-M-1 length but retain relatively long fibers, suggesting humans may have sacrificed relative masseter muscle force during chewing without appreciably altering muscle excursion/contraction velocity. Lastly, craniometric estimates of PCSAs underestimate hominoid masseter and temporalis PCSAs by more than 50% in gorillas, and overestimate masseter PCSA by as much as 30% in humans. These findings underscore the difficulty of accurately estimating jaw-muscle fiber architecture from craniometric measures and suggest models of fossil hominin and hominoid bite forces will be improved by incorporating architectural data in estimating jaw-muscle forces. Am J Phys Anthropol 151:120-134, 2013. (C) 2013 Wiley Periodicals, Inc.
Taylor A B; Vinyard C J
American Journal of Physical Anthropology
2013
2013-05
Journal Article
<a href="http://doi.org/10.1002/ajpa.22260" target="_blank" rel="noreferrer noopener">10.1002/ajpa.22260</a>