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Major stages in the evolution of the eye in vertebrates. Many scientists have found the evolution of the eye attractive to study because the eye distinctively exemplifies an analogous organ found in many animal forms. Simple light detection is found in bacteria, single-celled organisms, plants and animals.
The evolution of color vision in primates is highly unusual compared to most eutherian mammals. A remote vertebrate ancestor of primates possessed tetrachromacy , [ 1 ] but nocturnal , warm-blooded , mammalian ancestors lost two of four cones in the retina at the time of dinosaurs .
Ape skeletons. A display at the Museum of Zoology, University of Cambridge.From left to right: Bornean orangutan, two western gorillas, chimpanzee, human. The evolution of human bipedalism, which began in primates approximately four million years ago, [1] or as early as seven million years ago with Sahelanthropus, [2] [3] or approximately twelve million years ago with Danuvius guggenmosi, has ...
In the book vertebrate evolution is studied utilizing comparative anatomy & functional morphology of existing vertebrates, and fossil records. The book is considered a classic and has been used very frequently as a college-level or university introductory level text on the subjects of basic paleontology and vertebrate evolution. [2]
The eye is essentially a derivative of the ectoderm from the somatic ectoderm and neural tube, with a succession of inductions by the chordamesoderm. Chordamesoderm induces the anterior portion of the neural tube to form the precursors of the synapomorphic tripartite brain of vertebrates, and it will form a bulge called the diencephalon.
The frontal eye, which expresses the PAX6 gene, has been proposed as the homolog of vertebrate paired eyes,or the pineal eye on vertebrates, the pigment cup as the homolog of the RPE (retinal pigment epithelium), the putative photoreceptors as homologs of vertebrate rods and cones, and Row 2 neurons as homologs of the retinal ganglion cells. [60]
A lobster is heavily cephalized, with eyes, antennae, multiple mouthparts, and the brain (inside the armoured exoskeleton), all concentrated at the animal's head end. Cephalization is an evolutionary trend in animals that, over a sufficient number of generations, concentrates the special sense organs and nerve ganglia towards the front of the ...
Responsible for this process in mammals is the visual sensory system, the foundations of which were formed at an early stage in the evolution of chordates. Its peripheral part is formed by the eyes, the intermediate (by the transmission of nerve impulses) - the optic nerves, and the central - the visual centers in the cerebral cortex.