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A new basal actinopterygian fish from the Anisian (Middle Triassic) of Luoping, Yunnan Province, Southwest China

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Wen W., Zhang Q.-Y., Hu S.-X., Zhou C.-Y., Xie T., Huang J.-Y., Chen Z. Q., Benton M. J.

Acta Palaeontologica Polonica

2012

tom 57

nr 1

The new neopterygian fish taxon Luoxiongichthys hyperdorsalis gen. et sp. nov. is established on the basis of five specimens from the second member of the Guanling Formation (Anisian, Middle Triassic) from Daaozi Quarry, Luoping, Yunnan Province, Southwest China. The new taxon is characterized by the following characters: triangular body outline with a distinct apex located between skull and dorsal fin; free maxilla; slender preopercular almost vertical; three suborbitals; at least eight strong branchiostegals with tubercles and comb−like ornamentation on the anterior margin; clavicles present; two postcleithra; ganoid scales covered by tubercles and pectinate ornamentation on the posterior margin with peg−and−socket structure; hemiheterocercal tail slightly forked. Comparison with basal actinopterygians reveals that the new taxon has parasemionotid−like triangular symplectics, but a semionotid opercular system. Cladistic analysis suggests that this new genus is a holostean, and either a basal halecomorph or basal semionotiform.

Coelacanths from the Middle Triassic Luoping Biota, Yunnan, South China, with the earliest evidence of ovoviviparity

100%

Wen W., Zhang Q.-Y., Hu S.-X., Benton M. J., Zhou C.-Y., Tao X., Huang J.-Y., Chen Z.-Q.

Acta Palaeontologica Polonica

2013

tom 58

nr 1

The fossil record of coelacanths is patchy, with very few taxa known from the Triassic of Asia. We report here two new genera and species of coelacanths from the Luoping Biota, a recently found site of exceptional fossil preservation from Yunnan, South China. The first new taxon, Luopingcoelacanthus eurylacrimalis, is based on four specimens, which to− gether show most aspects of the anatomy. One specimen shows two small coelacanths inside the ventral portion of the ab− dominal cavity, and these are interpreted as intrauterine embryos, close to birth size, based on comparisons with previ− ously reported embryos of the fossil coelacanths Rhabdoderma and Undina, and the extant genus Latimeria. Our new find extends the evidence for ovoviviparity in coelacanths back from the Late Jurassic to the Middle Triassic. The second new taxon, Yunnancoelacanthus acrotuberculatus, is based on one specimen, and differs from Luopingcoelacanthus in the dentary, lachrymojugal, number of rays of the first dorsal fin, and especially in the ornament on dermal bones and scales. Acladistic analysis shows that the new taxa are closest relatives to the derived clade Latimerioidei. The relatively high di− versity of coelacanths in the Early Triassic, and adaptations of living Latimeria to low−oxygen conditions, suggests that the group may have included ‘disaster taxa’ that benefited from anoxic and dysoxic ocean conditions in the aftermath of the end−Permian mass extinction.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Benton M. J.

2 Hu S.-X.

2 Huang J.-Y.

2 Wen W.

2 Zhang Q.-Y.

2 Zhou C.-Y.

1 Chen Z. Q.

1 Chen Z.-Q.

1 Tao X.

1 Xie T.

1 2013

1 2012

Wyniki wyszukiwania

A new basal actinopterygian fish from the Anisian (Middle Triassic) of Luoping, Yunnan Province, Southwest China

Coelacanths from the Middle Triassic Luoping Biota, Yunnan, South China, with the earliest evidence of ovoviviparity