Nautilus taiwanus

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Nautilus taiwanus
Temporal range: Miocene
Nautilus taiwanus.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Nautiloidea
Order: Nautilida
Family: Nautilidae
Genus: Nautilus
Species:
N. taiwanus
Binomial name
Nautilus taiwanus
(Huang, 2002)
Synonyms
  • Kummelonautilus taiwanumHuang, 2002
  • Kummeloceras taiwanum(Huang, 2002)
  • Sinautilus taiwanicusTao & Hu, 2005 (Missp.)

Nautilus taiwanus is an extinct species of nautiloid, the fossils of which were found in the Shimen and Houdongkeng formations, of the early Miocene, in Nantou County, Taiwan. [1] [2]

The species was once classified as Kummelonautilus taiwanum, [1] but reclassified under Nautilus taiwanus in 2022, when it was recognised as the northernmost fossil record of the genus Nautilus in the Neogene Indo-Pacific. [2]

Discovery and research history

Most of the Nautilus fossils in Taiwan were found in Nantou County. The first Nautilus fossil was recorded by Ichiro Hayasaka in 1936, which was found in the present-day Ganzilin, Guoxing Township Nantou County, and was considered to belong to the Miocene strata. [3]

In 2002, a Nautilus fossil from Shimen formation in Zhongliao Township in Nantou was classified as a new species, Kummelonautilus taiwanum, but it was not clearly distinguished from other nautilus groups. [1] In another study in 2005, the identification characteristics of Kummelonautilus taiwanum were provided, but it still provided no diagnostic autapomorphy to distinguish it from other nautilus species. [4]

In 2022, a study re-examined the holotype and paratype, along with the new specimens found in the early Miocene Houdongkeng formation in Qiangou, Guoxing Township, Nantou County, Taiwan, suggesting that Kummelonautilus taiwanum belongs to the genus Nautilus. Further, as the morphological evolution of the cephalopod shell is conservative, the authors also suggest that the nautilus fossils from the Indo-Pacific region should be grouped into one genus rather than separate genera. However, due to the lack or incomplete preservation of Neogene specimens of the genus Nautilus, there are currently no morphological characteristics that can distinguish the type specimen of Nautilus taiwanus from other Nautilus species in Miocene Indonesia, Australia, or extant species. Therefore, "Nautilus taiwanus" is considered as a provisional name for this species until further comparative studies are conducted to clarify its taxonomic status. [2]

Nautilus taiwanus is presently considered to be the northernmost fossil record of the genus Nautilus in the Indo-Pacific region in the Neogene. [2] A hypothesis suggests that the regional extinction of nautiluses in the Cenozoic was associated with the occurrence of Pinnipedia and cetaceans, and that the record of nautiluses declined significantly or even disappeared after the occurrence of these marine mammals in some areas. [5]

Related Research Articles

<span class="mw-page-title-main">Nautilus</span> Family of molluscs

The nautilus is an ancient pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina.

<i>Balaenoptera</i> Genus of mammals

Balaenoptera is a genus of rorquals containing eight extant species. Balaenoptera comprises all but two of the extant species in its family ; the genus is currently polyphyletic, with the two aforementioned species being phylogenetically nested within it.

<span class="mw-page-title-main">Nautilida</span> Order of cephalopods

The Nautilida constitute a large and diverse order of generally coiled nautiloid cephalopods that began in the mid Paleozoic and continues to the present with a single family, the Nautilidae which includes two genera, Nautilus and Allonautilus, with six species. All told, between 22 and 34 families and 165 to 184 genera have been recognised, making this the largest order of the subclass Nautiloidea.

<span class="mw-page-title-main">Nautiloid</span> Extant subclass of cephalopods

Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living Nautilus and Allonautilus. Fossil nautiloids are diverse and species rich, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms (orthocones). No orthoconic and only a handful of coiled species, the nautiluses, survive to the present day.

<i>Baculites</i> Genus of molluscs (fossil)

Baculites is an extinct genus of heteromorph ammonite cephalopods with almost straight shells. The genus, which lived worldwide throughout most of the Late Cretaceous, and which briefly survived the K-Pg mass extinction event, was named by Lamarck in 1799.

<i>Osteodontornis</i> Extinct genus of birds

Osteodontornis is an extinct seabird genus. It contains a single named species, Osteodontornis orri, which was described quite exactly one century after the first species of the Pelagornithidae was. O. orri was named after Santa Barbara Museum of Natural History paleontologist Phil C. Orr, for his recognition of the importance of the specimen.

<i>Nautilus</i> (genus) Genus of molluscs

Nautilus is a marine cephalopod genus in the mollusk family Nautilidae. Species in this genus differ significantly, morphologically, from the two nautilus species in the adjacent sister-taxon Allonautilus. The oldest fossils of the genus are known from the Late Eocene Hoko River Formation, in Washington State and from Late-Eocene to Early Oligocene sediments in Kazakhstan. The oldest fossils of the modern species Nautilus pompilius are from Early Pleistocene sediments off the coast of Luzon in the Philippines.

<i>Nautilus cookanus</i> Extinct species of mollusc

Nautilus cookanus is an extinct species of nautilus. It lived during the Eocene epoch. N. cookanus placed within the genus Nautilus, together with extant species based on their shared shell characters. Fossils of the species from the Late Eocene Hoko River Formation are noted as one of the two oldest occurrences for the genus. Its name has frequently been misspelled as "cookanum".

<i>Nautilus praepompilius</i> Extinct species of mollusc

Nautilus praepompilius is an extinct species of nautilus. It lived from the Late Paleocene through Oligocene epochs. The first fossil specimens discovered in the Late Eocene to Oligocene-aged Chegan Formation of Kazakhstan: an additional, older specimen was found in the Late or Latest Paleocene-aged Pebble Point Formation in Victoria, Australia. N. praepompilius has been grouped into a single genus together with extant species based on their shared shell characters. It is morphologically closest to N. pompilius, hence the name. The nepionic constriction shows that the hatching size was approximately 23 mm, close to that for N. pompilius. N. praepompilius, along with aff. N. cookanum fossils from the late Eocene Hoko River Formation in Washington state are the oldest occurrences of the genus.

<i>Mene</i> Genus of fishes

The moonfish of the genus Mene, the sole extant genus of the family Menidae, are disk-shaped fish which bear a vague resemblance to gourami, thanks to their thread-like pelvic fins. Today, the genus is represented only by Mene maculata of the Indo-Pacific, where it is a popular food fish, especially in the Philippines, where it is known as bilong-bilong, chabita, hiwas or tahas.

Pseudodontornis is a rather disputed genus of the prehistoric pseudotooth birds. The pseudotooth birds or pelagornithids were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty. Up to five species are commonly recognized in this genus.

<i>Aturia</i> Extinct genus of molluscs

Aturia is an extinct genus of Paleocene to Miocene nautilids within Aturiidae, a monotypic family, established by Campman in 1857 for Aturia Bronn, 1838, and is included in the superfamily Nautilaceae in Kümmel 1964.

<i>Gryposuchus</i> Extinct genus of gavialoid crocodilian

Gryposuchus is an extinct genus of gavialid crocodilian. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the Miocene epoch. One recently described species, G. croizati, grew to an estimated length of 10 metres (33 ft). Gryposuchus is the type genus of the subfamily Gryposuchinae, although a 2018 study indicates that Gryposuchinae and Gryposuchus might be paraphyletic and rather an evolutionary grade towards the gharial.

<span class="mw-page-title-main">Hoko River Formation</span> Late Eocene marine sedimentary geologic formation

The Hoko River Formation is a Late Eocene marine sedimentary geologic formation. The formation is exposed in outcrops along the Strait of Juan de Fuca on the Olympic Peninsula in Washington state, USA. It is known for containing numerous fossils of crabs. It overlies the older Lyre Formation and underlies the younger Makah Formation.

<i>Eutrephoceras</i> Extinct genus of molluscs

Eutrephoceras is an extinct genus of nautilus from the Late Jurassic to the Miocene. They are characterized by a highly rounded involute shell with slightly sinuous suture patterns.

<i>Polymerichthys</i> Extinct genus of fishes

Polymerichthys is an extinct genus of superficially eel-like aulopiform fish known from the late Oligocene to the middle-late Miocene. It contains a single described species, P. nagurai from the Middle Miocene of Japan, though several indeterminate specimens are also known from Russia and Italy.

This list, 2016 in molluscan paleontology, is a list of new taxa of ammonites and other fossil cephalopods, as well as fossil gastropods, bivalves and other molluscs that have been described during the year 2016.

This list 2019 in paleomalacology is a list of new taxa of ammonites and other fossil cephalopods, as well as fossil gastropods, bivalves and other molluscs that are scheduled to be described during the year 2019, as well as other significant discoveries and events related to molluscan paleontology that are scheduled to occur in the year 2019.

This list of fossil molluscs described in 2022 is a list of new taxa of fossil molluscs that were described during the year 2022, as well as other significant discoveries and events related to molluscan paleontology that occurred in 2022.

This list of fossil molluscs described in 2023 is a list of new taxa of fossil molluscs that were described during the year 2023, as well as other significant discoveries and events related to molluscan paleontology that occurred in 2023.

References

  1. 1 2 3 Huang, T. (2002). "Kummelonautilus taiwanum, sp. nov. (Nautilida) from the early Miocene Shichmen Formation, Chungliao, Nantou, west-Central Taiwan". Western Pacific Earth Sciences. 2: 445–454.
  2. 1 2 3 4 "Miocene Nautilus (Mollusca, Cephalopoda) from Taiwan, and a review of the Indo-Pacific fossil record of Nautilus". Archived from the original on 2022-06-09. Retrieved 2022-06-09.
  3. Hayasaka, I. (1936). "A fossil Nautilus from Taiwan. Taiwan". Chigaku Kizi. 7: 65–67.
  4. "臺灣南投縣中寮鄉鸚鵡螺動物群" [Nautilus fauna in Zhongliao Township, Nantou County, Taiwan](PDF) (in Chinese). Archived from the original (PDF) on 2019-12-14. Retrieved 2019-12-14.
  5. Kiel, Steffen; Goedert, James L.; Tsai, Cheng‐Hsiu (2022-09-27). "Seals, whales and the Cenozoic decline of nautiloid cephalopods". Journal of Biogeography. 49 (11). doi: 10.1111/jbi.14488 . ISSN   0305-0270.