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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 heads of vertebrates are complex structures, with distinct sense organs for sight, olfaction, and hearing, [12] and a large, multi-lobed brain protected by a skull of bone or cartilage. [13] Cephalochordates like the lancelet ( Amphioxus ), a small fishlike animal with very little cephalization, are closely related to vertebrates but do not ...
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]
Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) ' without ' and γνάθος (gnáthos) ' jaws ') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ostracoderms, among others).
A newfound fossil of a jawless fish is the oldest known vertebrate cranium preserved in 3D. The 455 million-year-old find could illuminate how vertebrate heads evolved.
Several layers such as the neural tube, neural crest, surface ectoderm, and mesoderm contribute to the development of the eye. [2] [3] [4] Eye development is initiated by the master control gene PAX6, a homeobox gene with known homologues in humans (aniridia), mice (small eye), and Drosophila (eyeless). The PAX6 gene locus is a transcription ...
Classical spindle diagram of the evolution of the vertebrates at class level. The "traditional" vertebrate classification scheme employ evolutionary taxonomy where several of the taxa listed are paraphyletic, i.e. have given rise to another taxa that have been given the same rank.
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.