''Materpiscis'' (

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

for ''mother fish'') is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of ptyctodontid placoderm from the Late Devonian located at the

Gogo Formation The Gogo Formation in the Kimberley region of Western Australia is a Lagerstätte that exhibits exceptional preservation of a Devonian reef community. The formation is named after Gogo Station, a cattle station where outcrops appear and fossil ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. Known from only one specimen, it is unique in having an unborn embryo present inside the mother, with remarkable preservation of a mineralised placental feeding structure (

umbilical cord In placental mammals, the umbilical cord (also called the navel string, birth cord or ''funiculus umbilicalis'') is a conduit between the developing embryo or fetus and the placenta. During prenatal development, the umbilical cord is physiologi ...

). This makes ''Materpiscis'' the oldest known

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

to show

viviparity Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...

, or giving birth to live young.

Discovery and naming

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

was found in the Kimberley area of northern

by Lindsay Hatcher during the 2005 expedition to the Gogo led by John Long of

Museum Victoria Museums Victoria is an organisation which operates three major state-owned museums in Melbourne, Victoria: the Melbourne Museum, the Immigration Museum and Scienceworks Museum. It also manages the Royal Exhibition Building and a storage facili ...

. Fossils from the Gogo Formation are preserved in

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

nodules, so dilute acetic acid is used to dissolve the surrounding limestone and reveal the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

, often preserved in three dimensions with minimal distortion. The species was named ''Materpiscis attenboroughi'' in honour of David Attenborough who first drew attention to the significance of the Gogo fish sites in his 1979 series ''Life on Earth''.

Paleobiology

''Materpiscis'' would have been about long and had powerful crushing tooth plates to grind up its prey, possibly hard shelled invertebrates like clams or corals. Examination of the tail section of the holotype led to the discovery of the partially ossified skeleton of a juvenile ''Materpiscis'' and the mineralised umbilical cord. The team published their findings in 2008. The juvenile ''Materpiscis'' was about 25 percent of its adult size. The large size of the embryo relative to the mother indicates that the young of this fish were born well-formed, a strategy that may have evolved to counter predation from other larger fishes. The ptyctodontid fishes are the only group of placoderms to display

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

, where

male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot reproduce sexually without access to ...

s have clasping organs and

female Female ( symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. A female has larger gametes than a male. Females ...

s have smooth pelvic fin bases. It had long been suspected that they reproduced using

internal fertilisation Internal fertilization is the union of an egg and sperm cell during sexual reproduction inside the female body. Internal fertilization, unlike its counterpart, external fertilization, brings more control to the female with reproduction. For int ...

, but finding fossilised embryos inside both ''Materpiscis'' and in a similar form also from Gogo, ''Austroptyctodus'', proved the deduction was true.

In popular culture

*''Materpiscis attenboroughi'' was selected as one of ''"The Top 10 New Species"'' described in 2008 by The International Institute for Species Exploration at Arizona State University and an international committee of

taxonomists In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...

.Pea-sized Seahorse, Bacteria That Life In Hairspray, Caffeine-free Coffee Among Top 10 New Species Of 2008 Science Daily May 23, 2009
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References

{{Taxonbar, from=Q131787 Ptyctodontids Gogo fauna Fossil taxa described in 2008 Placoderm genera

Discovery and naming

Paleobiology

In popular culture

See also

References