A member of the jawed-vertebrate lineage. Crown usage includes the ancestor of living cartilaginous and bony vertebrates and all its descendants; a total-group usage additionally includes jawless stem relatives. The usage must be stated when discussing early fossils.
A member of an extinct armoured jawless lineage with differentiated pectoral fins and usually recovered close to jawed vertebrates.
A member of an extinct armoured jawless lineage commonly placed on the gnathostome stem outside osteostracans and jawed vertebrates.
A Silurian jawless vertebrate preserving continuous paired ventrolateral fins, interpreted as a precursor to more localized paired appendages.
An Early Devonian stem jawed vertebrate combining an extensively ossified dermal roof with informative braincase anatomy.
An armoured jawed fish in a traditional Palaeozoic assemblage. Whether the assemblage is monophyletic or a succession of branches affects ancestral state reconstruction.
An Early Devonian Siberian jawed vertebrate whose braincase–shoulder relationship supplies evidence for a posterior pharyngeal component of the pectoral girdle.
An Early Devonian Mongolian jawed vertebrate whose braincase contains a trabecular internal tissue interpreted as endochondral bone. Implications for ancestral bone depend on both tissue identity and phylogenetic placement.
A Silurian armoured jawed vertebrate with large marginal jaw bones previously associated with bony vertebrates.
A member of a traditionally recognized assemblage of Palaeozoic spiny jawed fishes. Many analyses resolve these taxa as a succession on the Chondrichthyes stem rather than a separate complete clade.
The cartilaginous-fish clade, including sharks, ray fish and chimaeras. Extant lack of extensive bone does not demonstrate that their ancestors never possessed it.
The little skate, used experimentally to compare branchial and appendage patterning.
An Early Silurian jawed vertebrate known from mineralized tooth whorls, illustrating the information carried by isolated hard parts.
The bony-vertebrate lineage including ray-finned vertebrates and Sarcopterygii; descendants remain members even after extensive modification of their ancestral skeleton.
A ray-finned vertebrate whose skin expression of enamel-matrix genes contributes to comparisons of enamel and ganoine evolution.
A fossil bony vertebrate whose dermal odontodes preserve enamel despite teeth without an enamel coating, important for separating tissue origin from oral deployment.
In crown-based usage, the clade comprising the most recent common ancestor of living coelacanths, lungfish and tetrapods, and all its descendants. Lobed, internally supported paired appendages provide a traditional diagnostic character; inherited organization can persist despite conversion of fins into limbs.
A finned Devonian relative of digit-bearing vertebrates. Its pectoral skeleton combines retained fin rays with jointed internal structures relevant to limb evolution.
A member of the coelacanth lineage of sarcopterygians. Living representatives are specialized descendants, not unchanged ancestral fish.
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