Tinirau clackae

Tinirau clackae; Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Holotype fossil and interpretive drawing of Tinirau clackae
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Sarcopterygii
Clade:	Tetrapodomorpha
Clade:	Eotetrapodiformes
Genus:	†Tinirau; Swartz, 2012
Species:	†T. clackae
Binomial name
	†Tinirau clackae; Swartz, 2012
Synonyms
	Bruehnopteron murphyi Schultze & Reed (2012)?

Tinirau is an extinct

Tetrapoda. Relative to more well-known stem tetrapods, Tinirau is more closely related to Tetrapoda than is Eusthenopteron, but farther from Tetrapoda than is Panderichthys. The type and only species of Tinirau is T. clackae, named in 2012.^[2]

Description

Tinirau was a fairly large, predatory fish about a meter long and with a deep, compact body. The head was large, with large terminal mout and numerous teeth. The tail was

pectoral fins were situated behind the middle of the body similar to the situation seen in pikes

, giving the animal a large tail surface suitable for great bursts of speed.

It shares many advanced features with later tetrapodomorphs in the

fibulare bone below it. Tinirau is the earliest known stem tetrapod to have a significantly reduced postaxial process, and a fibula more like those of later tetrapods.^[2]

Like those of the Late Devonian Panderichthys and Ichthyostega, the glenoid of Tinirau is elongated along the anteroposterior (forward-backward) axis of the body. The lengthening of the glenoid corresponds with a flattening of the proximal end of the humerus, a feature common in the forelimbs of more advanced stem tetrapods. Although the pectoral limb bones and girdle were not strong enough to support the weight of Tinirau out of water, glenoid lengthening and other changes to the proximal forelimb were among the first steps in the transformation from pectoral fin to forelimb.^[2]

History

Remains of Tinirau were first discovered by paleontologist

outer continental shelf marine environment. Six fossils are known, all preserving bones of the skull. Two fossils preserve postcranial bones in articulation. The holotype specimen, UCMP 118605, is a mostly complete skeleton.^[2]

Tinirau clackae was named by paleontologist Brian Swartz in 2012 after

Jennifer A. Clack, an English paleontologist who has made many contributions to the study of stem tetrapods.^[2]

Phylogeny

In

tristichopterids. In its first description, the phylogenetic analysis of Swartz placed Tinirau as a branch directly connected to the stem of Tetrapoda. In other words, it is a close relative of the lineage leading to land vertebrates (a prehistoric taxon can rarely be identified as an ancestor of another taxon, but is instead considered a side branch in a larger lineage). Eusthenopteron, traditionally considered a direct ancestor of tetrapods, or a close relative of such an ancestor, was placed deep within the family Tristichopteridae, away from the tetrapod stem. Below is a cladogram modified from Swartz (2012) showing the placement of Tinirau:^[2]

Tetrapodomorpha

Kenichthys

Rhizodontidae