A member of the chordate lineage that includes jawless and jawed vertebrates. Features of the head, neural crest and internal skeleton vary across its descendant groups.
A Cambrian fossil animal with evidence of segmented musculature, sensory anatomy and serial branchial structures.
A Chengjiang fossil animal described with Haikouichthys in studies of early vertebrate organization.
A traditional assemblage of armoured jawless fossil vertebrates. It is not a complete clade, and many members are stem relatives of gnathostomes, rather than early cyclostomes.
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.
A member of the lineage uniting living hagfish and lampreys. Jawlessness alone cannot assign an extinct vertebrate to this lineage.
A jawless vertebrate lineage with a specialized oral apparatus. Living lamprey anatomy is informative without being a direct reconstruction of the ancestral vertebrate.
A Late Devonian fossil lamprey from South Africa preserving diagnostic anatomy in an exceptional soft-tissue window.
A jawless vertebrate with a strongly specialized feeding apparatus and slime-producing system. Soft-tissue anatomy and secondary modifications make the ordinary fossil record difficult to interpret.
A Cretaceous fossil hagfish preserving evidence of specialized soft-tissue anatomy, including slime-producing structures.
A vertebrate belonging to the lineage of four-limbed vertebrates, including descendants whose limbs were reduced or lost.
A Devonian digit-bearing vertebrate with eight anatomical digits in the forelimb, demonstrating that a five-digit condition was not universal in early limbs.
The posterior paired limb of the tetrapod body plan. A reduced limb can lose its locomotor role while retaining other functions.
The anterior paired limb of the tetrapod body plan, modified into structures including arms, wings and flippers.
A tetrapod in the lineage including synapsids and sauropsids, characterized ancestrally by embryonic membranes including an amnion.
The reptile-side amniote lineage, including birds. A traditional assemblage excluding birds does not contain all of this ancestry’s descendants.
A fossil reptile proposed as an early turtle relative. Its skull anatomy, ontogeny and phylogenetic placement have been used to test the history of temporal roof closure.
A reptile lineage with a two-opening temporal skull organization inferred in its ancestry. Modified descendants can lose or close these openings; turtles illustrate why present-day hole counts do not determine ancestry.
A member of the turtle lineage, whose shell and skull underwent substantial modification. Molecular and fossil evidence support a diapsid origin, with living turtles commonly recovered as sister to archosaurs.
A Middle Triassic stem relative of turtles combining modified ribs and ventral skeletal elements with temporal anatomy supporting a diapsid origin.
The clade comprising the most recent common ancestor of living crocodilians and birds and all its descendants, including extinct dinosaurs. Being sister to this clade does not make turtles archosaurs.
A member of the dinosaur lineage, including birds. Restricting the word to extinct nonavian forms excludes descendants.
A member of the theropod lineage of dinosaurs, within which birds are nested. The hands and integument of nonavian relatives inform comparisons of avian origins.
A name used for a more restricted avian-lineage clade than Panaves. Definitions have included a branch-based bird-versus-deinonychosaur rule and an apomorphy-based flight rule; the definition must be specified in comparative work.
A member of the avian lineage of theropod dinosaurs. The extent of the named group can differ between crown-based and broader fossil usages.
A toothed Late Cretaceous bird outside Aves in crown usage, important for comparisons of the avian skull.
A Late Jurassic avian-lineage theropod dinosaur outside the living-bird crown group under standard relationships.
Used here for the crown group of birds: the last common ancestor of living palaeognaths and neognaths and all descendants. Broader historical definitions also occur and should be stated explicitly.
The crown-bird lineage containing Galloanserae and other living birds outside Palaeognathae. Taxonomic membership and possession of a particular mobile palate are different claims.
The crown-bird lineage containing ostriches, emus, kiwis, tinamous and relatives. Its palaeognathous palate is an anatomical specialization, not evidence that its members are ancestors of neognaths.
A corvid, including Corvus corax, used in studies of social information and caching.
A radiation of Galápagos and nearby finches important in studies of ecological divergence, song and hybridization.
The owl called Tyto alba in the cited sibling-negotiation experiments.
A member of the living crocodilian lineage, including crocodiles and their closest living relatives. birds are its living sister lineage within Archosauria.
A living representative of the rhynchocephalian lineage. Including this branch helps test alternatives for turtle placement rather than equating all lepidosaur diversity with lizards.
A reptile taxon whose precise ancestry-based definition should be stated. clade usages include birds; the traditional everyday assemblage excluding birds is paraphyletic.
An amniote in the lineage containing mammals and their extinct relatives on the mammalian side of the split from sauropsids. The name does not mean a mammalian ancestor was a living reptile.
A synapsid in the lineage that includes cynodonts and mammals. Many therapsids lie outside the mammalian crown group.
A therapsid belonging to the group containing mammaliaforms and close extinct relatives. Enlargement of the dentary, differentiation of teeth and changes in the palate record a mosaic of feeding transformations.
A cynodont clade containing mammaliaforms and some close extinct relatives. It is broader than the living mammalian crown group.
A member of the lineage including mammals and close extinct relatives such as Morganucodon. Usage must distinguish this broader grouping from a living mammalian crown group.
A Middle Jurassic mammaliaform with aquatic adaptations and preserved integument. The fossil supplies a minimum occurrence for a fur-bearing covering, not the exact origin date of endothermy. [ref]
A swimming mammaliaform from the Middle Jurassic and ecomorphological diversification of early mammals by Qiang Ji and others. Science 311, pp. 1123–1127; Castorocauda skeleton and preserved integument
An Early Cretaceous mammal initially interpreted as a metatherian; later comparative analysis supported a eutherian placement, illustrating uncertainty in fossil assignment. [ref]
An Early Cretaceous eutherian and the placental–marsupial dichotomy by Shundong Bi and others. Nature 558, pp. 390–395; Ambolestes anatomy and revised placement of Sinodelphys
An extinct mammalian radiation historically known chiefly from teeth. New cranial and skeletal material permits wider tests of its uncertain relationships. [ref]
First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism by David W. Krause and others. Nature 515, pp. 512–517; Vintana cranium and phylogenetic character sampling
A latest Cretaceous Malagasy gondwanatherian with an unusually informative skeleton and a mosaic of anatomical features. [ref]
Skeleton of a Cretaceous mammal from Madagascar reflects long-term insularity by David W. Krause and others. Nature 581, pp. 421–427; Adalatherium skeleton and insularity hypothesis
A latest Cretaceous Malagasy gondwanatherian known from a well-preserved cranium. [ref]
First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism by David W. Krause and others. Nature 515, pp. 512–517; Vintana cranium and phylogenetic character sampling
A grouping used in hypotheses contrasting northern and southern origins of tribosphenic molars, including the lineage of therians.
A proposed southern mammaliaform grouping important to hypotheses of an independent southern origin of tribospheny. Membership and relationships have differed among analyses. [ref]
Dual origin of tribosphenic mammals by Zhe-Xi Luo and others. Nature 409, pp. 53–57; alternative placements of southern tribosphenic mammals
A Middle Jurassic Malagasy mammaliaform known from lower teeth in a jaw fragment. Its tribosphenic-like construction bears on competing hypotheses for the origin of tribospheny. [ref]
A Middle Jurassic mammal from Madagascar by John J. Flynn and others. Nature 401, pp. 57–60; Ambondro lower jaw, approximately 167 ± 2 million years old
An Early Jurassic mammaliaform with a small skull documenting changes in the jaw, ear attachment and braincase. [ref]
A new mammaliaform from the early Jurassic and evolution of mammalian characteristics by Zhe-Xi Luo and others. Science 292, pp. 1535–1540; Hadrocodium skull and jaw comparisons
An early mammaliaform whose jaw preserves both articular–quadrate and dentary–squamosal articulations.
For a crown-based usage, a member of the clade comprising the last common ancestor of living monotremes and therians and all its descendants. hair and lactation characterize living members, but recognition of many early fossils depends on jaw and dental characters.
Sorex minutus, a native Irish shrew.
Crocidura russula, an introduced shrew in Ireland first recorded there in 2007.
Native status is geographical: a species native in mainland Britain can be introduced to an offshore island.
An antelope studied for false alarm snorts associated with retaining receptive females.
Articles were limited to the first 100 out of 205 total.
