The generic nameMediocris (Cetacea: Delphinoidea: Kentriodontidae), belongs to a foraminiferan

No abstract available for this article.doi:10.1002/mmng.20060001

Form, Function, and Anatomy of Dorudon Atrox (Mammalia, Cetacea): An Archaeocete from the Middle to Late Eocene of Egypt

p. 1-222http://deepblue.lib.umich.edu/bitstream/2027.42/41255/1/529917textts.pd

Ancalecetus simonsi, A New Dorudontine Archaeocete (Mammalia, Cetacea) from the Early Late Eocene of Wadi Hitan, Egypt

359-401http://deepblue.lib.umich.edu/bitstream/2027.42/48634/2/ID500.pd

Reconstructing Cetacean Brain Evolution Using Computed Tomography

Until recently, there have been relatively few studies of brain mass and morphology in fossil cetaceans (dolphins, whales, and porpoises) because of difficulty accessing the matrix that fills the endocranial cavity of fossil cetacean skulls. As a result, our knowledge about cetacean brain evolution has been quite limited. By applying the noninvasive technique of computed tomography (CT) to visualize, measure, and reconstruct the endocranial morphology of fossil cetacean skulls, we can gain vastly more information at an unprecedented rate about cetacean brain evolution. Here, we discuss our method and demonstrate it with several examples from our fossil cetacean database. This approach will provide new insights into the little-known evolutionary history of cetacean brain evolution

Origin and Evolution of Large Brains in Toothed Whales

Toothed whales (order Cetacea: suborder Odontoceti) are highly encephalized, possessing brains that are significantly larger than expected for their body sizes. In particular, the odontocete superfamily Delphinoidea (dolphins, porpoises, belugas, and narwhals) comprises numerous species with encephalization levels second only to modern humans and greater than all other mammals. Odontocetes have also demonstrated behavioral faculties previously only ascribed to humans and, to some extent, other great apes. How did the large brains of odontocetes evolve? To begin to investigate this question, we quantified and averaged estimates of brain and body size for 36 fossil cetacean species using computed tomography and analyzed these data along with those for modern odontocetes. We provide the first description and statistical tests of the pattern of change in brain size relative to body size in cetaceans over 47 million years. We show that brain size increased significantly in two critical phases in the evolution of odontocetes. The first increase occurred with the origin of odontocetes from the ancestral group Archaeoceti near the Eocene-Oligocene boundary and was accompanied by a decrease in body size. The second occurred in the origin of Delphinoidea only by 15 million years ago

Evolution of Coryphodon (Mammalia, Pantodonta) in the Late Paleocene and Early Eocene of Northwestern Wyoming

259-289http://deepblue.lib.umich.edu/bitstream/2027.42/48649/2/ID516.pd

Cranial Morphology of Protosiren fraasi (Mammalia, Sirenia) from the Middle Eocene of Egypt: A New Study Using Computed Tomography

41-67http://deepblue.lib.umich.edu/bitstream/2027.42/48641/2/ID508.pd

The Pliocene marine megafauna extinction and its impact on functional diversity

The end of the Pliocene marked the beginning of a period of great climatic variability and sea-level oscillations. Here, based on a new analysis of the fossil record, we identify a previously unrecognized extinction event among marine megafauna (mammals, seabirds, turtles and sharks) during this time, with extinction rates three times higher than in the rest of the Cenozoic, and with 36% of Pliocene genera failing to survive into the Pleistocene. To gauge the potential consequences of this event for ecosystem functioning, we evaluate its impacts on functional diversity, focusing on the 86% of the megafauna genera that are associated with coastal habitats. Seven (14%) coastal functional entities (unique trait combinations) disappeared, along with 17% of functional richness (volume of the functional space). The origination of new genera during the Pleistocene created new functional entities and contributed to a functional shift of 21%, but minimally compensated for the functional space lost. Reconstructions show that from the late Pliocene onwards, the global area of the neritic zone significantly diminished and exhibited amplified fluctuations. We hypothesize that the abrupt loss of productive coastal habitats, potentially acting alongside oceanographic alterations, was a key extinction driver. The importance of area loss is supported by model analyses showing that animals with high energy requirements (homeotherms) were more susceptible to extinction. The extinction event we uncover here demonstrates that marine megafauna were more vulnerable to global environmental changes in the recent geological past than previously thought

Cetaceans have complex brains for complex cognition

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