Monotreme skulls can be distinguished from those of other mammals by: Mandible composed solely of the dentary.Upper teeth are present on the maxilla and premaxilla only.Three ear ossicles are present and enclosed in an auditory bulla on the basicranium.Most circumorbitals are lost, and the postorbital is either reduced or lost altogether.Nasal turbinals (aka nasal turbinates, nasal conchae) form from the maxillae, nasals, and/or mesethmoid.The mammalian skull has several characteristic features: See the terms list here: Terms 4.1 Some notes on mammal skulls After this lab, you will be able to identify the objects listed below in bold face in the articulated skull, and you will learn to identify the objects with asterisks (*) in isolation. When you are examining the mammal skulls, notice the robustness of the dentary and the skull overall, and consider the spaces and cavities and foramina that support the neural, visual, olfactory, and auditory systems. Mammals are alert for prey and vigilant against predators, and they have large brains and well-developed sense organs to monitor their surroundings. For mastication to be effective, the skull needs to be akinetic, the jaws need to be strong, and the masticatory muscles need to be powerful. Mammals masticate their food efficiently, reducing food items to relatively small particles with high surface area, and this facilitates the action of digestive enzymes and leads to more rapid assimilation. As a result of their high energetic demands, mammals need to obtain relatively more food than other vertebrates, and they must extract as much energy as possible from this food. Many changes to the mammal head are tied to these factors. Endothermy and high metabolic rates reflect active lifestyles, and mammals are highly active and alert to their surroundings. Mammals are endothermic animals with a very high metabolism. In this lab we will focus on the mammal skull. Study the major morphological differences within the mammalian clades Rodentia and Carnivora.Explore the evolution of the sense organs, with a focus on the auditory system.Distinguish among monotreme, marsupial, and placental mammal skulls based on morphology.Identify the bones and important features of the mammal skull.
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