Halecomorphs are Neopterygid Fish
(Ray-finned Fish) related to Ginglymodians (Gars) and Teleosts (almost all
modern Ray-finned Fish). They are split into three groups, the extant Amiiformes,
which contain a single living species, the Bowfin, Amia calva, the Paraseminotiformes, which are known from the Early
Triassic and possibly the Permian, and the Ionoscopiformes which are known from
the Middle Triassic to the Early Cretaceous. To date only a single Ionoscopiform
has been described from the Triassic, Robustichthys
from the Middle Triassic Panxian Biota of Guizhou Province, China, although
potential Ionoscopiformes have been described from the Middle Triassic of
Austria and Italy.
In a paper published in the
journal Vertebrata PalAsiatica on 21 January 2015, Xu Guang-Hi of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences and the State Key Laboratory of Palaeobiology and Stratigraphy at the Nanjing Institute of Geology and Palaeontology and Shen Chen-Chen, also of the
Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese
Academy of Sciences, describe a second species of Ionoscopiform Fish from the
Middle Triassic Panxian Biota of Guizhou Province, China.
The new species is named Panxianichthys imparilis, where ‘Panxianichthys’ means ‘Panxian-Fish’ and
‘imparilis’ meaning ‘peculiar and
unusual’. It is described from two specimens, both about 200 mm in length,
though which is the largest depends on how they are measured, since the smaller
specimen has a more intact tail.
Panxianichthys imparilis,
first specimen. Photograph (top) and interpretive drawing (bottom). Xu & Shen (2015).
The new species comes from the
same deposits as Robustichthys, Member
II of the Guanling Formation at Xinmin in Panxian County, though it is judged
to be slightly younger; these deposits have produced a variety of Fish, Marine
Reptiles and Invertebrates, which are collectively referred to as the ‘Panxian
Biota’ or ‘Panxian Fauna’. Importantly, while Panxianichthys is slightly younger than Robustichthys, it is judged to be slightly more primitive, which is
to say it shows less of the derived features seen in Ionoscopiform Fish but not
non-Ionoscopiform Halecomorphs, suggesting that it may be closer to the first
Ionoscopiform Fish, making it useful for understanding the origin and evolution
of the group.
Panxianichthys imparilis,
second specimen. Photograph (top) and interpretive drawing (bottom). Xu & Shen (2015).
See also…
A freshwater Coccolepidid Fish from the Late Jurassic of Patagonia.In 1943 palaeontologist Alejandro Bordas described a number of fossil freshwater Fish from a location in...
An Ichthyodectiform Fish from the Early Cretaceous of Queensland, Australia.Ichthyodectiforms were large, predatory Fish from the Late Jurassic and Cretaceous, distantly related to modern Mooneyes, Elephantfish, Featherbacks, Arowanas and Butterflyfish. The typically...
A Flying Fish from the Middle Triassic of Guizhou Province, China.Modern Flying Fish, Exocoetidae, are known in the fossil record as far back as the Eocene, and may have originated slightly earlier, though it is unlikely that they are much older than this, since they are known to be related to other groups considered to be quite...
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