The origin and early evolution of whales: macroevolution documented on the Indian Subcontinent

Bajpai, Sunil; Thewissen, J. G. M.; Sahni, Ashok

doi:10.1007/s12038-009-0060-0

Cited by 26 publications

(12 citation statements)

References 45 publications

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“…Within Laurasiatheria, there is no clear consensus for the relationships of the orders (Hallstrom et al , ; Hu et al , ), except that Carnivora and Pholidota are likely to be sister taxa (Nishihara et al , ; Zhou et al , ). Raoellid artiodactyls (including Indohyus ) are considered to be closer relatives of cetaceans than other artiodactyls in this analysis (Bajpai, Thewissen & Sahni, ), and as a result, the topologies within Artiodactyla were also constrained to reflect this basal division.…”

Section: Methodsmentioning

confidence: 99%

Resolving the relationships of Paleocene placental mammals

2015

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The 'Age of Mammals' began in the Paleocene epoch, the 10 million year interval immediately following the Cretaceous-Palaeogene mass extinction. The apparently rapid shift in mammalian ecomorphs from small, largely insectivorous forms to many small-to-large-bodied, diverse taxa has driven a hypothesis that the end-Cretaceous heralded an adaptive radiation in placental mammal evolution. However, the affinities of most Paleocene mammals have remained unresolved, despite significant advances in understanding the relationships of the extant orders, hindering efforts to reconstruct robustly the origin and early evolution of placental mammals. Here we present the largest cladistic analysis of Paleocene placentals to date, from a data matrix including 177 taxa (130 of which are Palaeogene) and 680 morphological characters. We improve the resolution of the relationships of several enigmatic Paleocene clades, including families of 'condylarths'. Protungulatum is resolved as a stem eutherian, meaning that no crown-placental mammal unambiguously pre-dates the Cretaceous-Palaeogene boundary. Our results support an Atlantogenata-Boreoeutheria split at the root of crown Placentalia, the presence of phenacodontids as closest relatives of Perissodactyla, the validity of Euungulata, and the placement of Arctocyonidae close to Carnivora. Periptychidae and Pantodonta are resolved as sister taxa, Leptictida and Cimolestidae are found to be stem eutherians, and Hyopsodontidae is highly polyphyletic. The inclusion of Paleocene taxa in a placental phylogeny alters interpretations of relationships and key events in mammalian evolutionary history. Paleocene mammals are an essential source of data for understanding fully the biotic dynamics associated with the end-Cretaceous mass extinction. The relationships presented here mark a critical first step towards accurate reconstruction of this important interval in the evolution of the modern fauna.

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Section: Methodsmentioning

confidence: 99%

Resolving the relationships of Paleocene placental mammals

2015

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“…Discussion. The fossil record famously illuminates the transition from terrestrial artiodactyls to fully aquatic cetaceans in substantial detail (Thewissen et al, 2009). What is somewhat less appreciated by the lay public is the fact that the major divergence within cetaceans, i.e., that between baleen (mysticete) and toothed (odontocete) whales from an archaeocete common ancestor, is also well documented paleontologically.…”

Section: Crown Cetacea (72)mentioning

confidence: 99%

Constraints on the timescale of animal evolutionary history

Benton

Donoghue

Asher

et al. 2015

Palaeontologia Electronica

195

322

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Calibrations published in the Fossil Calibration Series are accessioned into the Fossil Calibration Database (www.fossilcalibrations.org). The Database is a dynamic tool for finding up-to-date calibrations, and calibration data will be updated and annotated as interpretations change. In contrast, the Fossil Calibration papers are a permanent published record of the information on which the calibrations were originally based. Please refer to the Database for the latest data.

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“…All cetaceans evolved from a common ancestor of the Raoellidae family of artiodactyls, a deer-like terrestrial herbivorous creature the size of a raccoon, which lived about 48 million years ago (Bajpai et al, 2009). The closest extant cetacean relatives are the hippopotamids followed by the ruminants (Figure 4).…”

Section: Cetacean and B Ceti Phylogeny And Host–pathogen Coevolutionmentioning

confidence: 99%

Brucella ceti and Brucellosis in Cetaceans

Guzmán-Verri¹,

González-Barrientos²,

Hernández-Mora³

et al. 2012

Front. Cell. Inf. Microbio.

127

178

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Since the first case of brucellosis detected in a dolphin aborted fetus, an increasing number of Brucella ceti isolates has been reported in members of the two suborders of cetaceans: Mysticeti and Odontoceti. Serological surveys have shown that cetacean brucellosis may be distributed worldwide in the oceans. Although all B. ceti isolates have been included within the same species, three different groups have been recognized according to their preferred host, bacteriological properties, and distinct genetic traits: B. ceti dolphin type, B. ceti porpoise type, and B. ceti human type. It seems that B. ceti porpoise type is more closely related to B. ceti human isolates and B. pinnipedialis group, while B. ceti dolphin type seems ancestral to them. Based on comparative phylogenetic analysis, it is feasible that the B. ceti ancestor radiated in a terrestrial artiodactyl host close to the Raoellidae family about 58 million years ago. The more likely mode of transmission of B. ceti seems to be through sexual intercourse, maternal feeding, aborted fetuses, placental tissues, vertical transmission from mother to the fetus or through fish or helminth reservoirs. The B. ceti dolphin and porpoise types seem to display variable virulence in land animal models and low infectivity for humans. However, brucellosis in some dolphins and porpoises has been demonstrated to be a severe chronic disease, displaying significant clinical and pathological signs related to abortions, male infertility, neurobrucellosis, cardiopathies, bone and skin lesions, strandings, and death.

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The origin and early evolution of whales: macroevolution documented on the Indian Subcontinent

Cited by 26 publications

References 45 publications

Resolving the relationships of Paleocene placental mammals

Resolving the relationships of Paleocene placental mammals

Constraints on the timescale of animal evolutionary history

Brucella ceti and Brucellosis in Cetaceans

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