Nautilus taiwanus

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Nautilus taiwanus
Temporal range: Miocene
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 Nautilus . The fossils were found in the Shimen formation and the Houdongkeng formation of the early Miocene in Nantou County. [1] [2]

This species was once classified as Kummelonautilus taiwanum, [1] but reclassified in 2022 as Nautilus taiwanus and recognized as the northernmost fossil record of this genus 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">Neogene</span> Second geologic period in the Cenozoic Era 23–2.6 million years ago

The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago (Mya) to the beginning of the present Quaternary Period 2.58 million years ago. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868).

<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 of its smaller but near equal 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">Argonautidae</span> Family of molluscs

The Argonautidae are a family of pelagic cephalopods that inhabit tropical and temperate oceans of the world. The family encompasses the modern paper nautiluses of the genus Argonauta along with several extinct genera of shelled octopods. Though argonauts are derived from benthic octopuses, they have evolved to depart the sea floor and live their life-cycle in the open seas.

<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 speciose, 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). Only a handful of rare coiled species, the nautiluses, survive to the present day.

<i>Diceros</i> Genus of Rhinocerotidae

Diceros is a genus of rhinoceros containing the extant black rhinoceros (Diceros bicornis) and several extinct species.

<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 the naturalist Ellison Orr (1857-1951).

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

Nautilus is a genus of cephalopods in the family Nautilidae. Species in this genus differ significantly in terms of morphology from those placed in the 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>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.

<i>Metaxytherium</i> Extinct genus of dugong

Metaxytherium is an extinct genus of dugong that lived from the Oligocene until the end of the Pliocene. Fossil remains have been found in Africa, Europe, North America and South America. Generally marine seagrass specialists, they inhabited the warm and shallow waters of the Paratethys, Mediterranean, Caribbean Sea and Pacific coastline. American species of Metaxytherium are considered to be ancestral to the North Pacific family Hydrodamalinae, which includes the giant Steller's Sea Cow.

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

Pelagornis is a widespread genus of prehistoric pseudotooth birds. These were probably rather close relatives of either pelicans and storks, or waterfowl, and are placed here in the order Odontopterygiformes to account for this uncertainty.

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>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.

<i>Hypolagus</i> Extinct genus of lagomorph

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<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.

<span class="mw-page-title-main">Pisco Formation</span> Geologic formation in Peru

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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.

Kelenkura is an extinct genus of heavily armored mammals belonging to the subfamily Glyptodontinae, from the family Chlamyphoridae that contain most of the modern armadillos. It was a medium-sized South American animal, distantly related to Doedicurus. Fossils of this genus were recovered in the Arroyo Chasicó Formation and in the Loma de Las Tapias Formation of Argentina in rocks dating back to the Late Miocene epoch.

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.