Knowra Vertebrate evolution Vertebrate evolution Vertebrate evolution is the history of evolutionary change in animals with backbones, from early aquatic ancestors to fishes, tetrapods, and their living descendants.
Cambrian explosion : A geologically brief interval when many major animal groups first appear in the fossil record. Cambrian fossils record early diversification among animals near vertebrate origins.
Vertebrate : An animal in the chordate group Vertebrata, typically characterized by a backbone or its developmental precursor. The group’s shared anatomy provides the framework for tracing evolutionary changes.
Chordate : An animal in the phylum Chordata, whose members possess a notochord at least during development. Vertebrates are one branch of the broader chordate lineage.
Tiktaalik : An extinct Devonian vertebrate with fish features and limb-like fins, discovered in Arctic Canada. Its anatomy documents a transitional combination near the origin of limbed vertebrates.
Linnaean taxonomy : A hierarchical system of naming and classifying organisms using ranked categories such as genus and family. Traditional ranks can obscure branching ancestry when lineages diversify unevenly.
Haikouichthys : An extinct Cambrian animal known from fossils in China, often classified among the earliest vertebrates. Its fossil anatomy offers evidence about the earliest recognizable vertebrates.
Vertebral column : A segmented axial structure that supports the body and, in most vertebrates, surrounds the spinal cord. Its changing form records a defining structural feature of vertebrate history.
Fossil : Preserved remains, traces, or chemical evidence of past life. Fossils provide the direct record used to reconstruct extinct vertebrate forms.
Acanthostega : An extinct Devonian stem tetrapod with digits, adapted primarily to life in water. It shows that digits evolved before tetrapods became fully terrestrial.
Evolutionary grade : A group of organisms sharing a general level of anatomical or ecological organization, not necessarily a complete clade. Some familiar groupings, such as traditional “fishes,” describe grades rather than single branches.
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