''Materpiscis'' (
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
for ''mother fish'') is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
ptyctodontid placoderm
Placoderms (from Ancient Greek πλάξ 'plax'', ''plakos'''Plate (animal anatomy), plate' and δέρμα 'derma'''skin') are vertebrate animals of the class (biology), class Placodermi, an extinct group of prehistoric fish known from Pal ...
from the
Late Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...
located at the
Gogo Formation of
Western Australia
Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
. Known from only one specimen, it is unique in having an unborn
embryo
An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
present inside the mother, with remarkable preservation of a mineralised placental feeding structure (
umbilical cord
In Placentalia, 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 i ...
). This makes ''Materpiscis'' the oldest known
vertebrate
Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain.
The vertebrates make up the subphylum Vertebra ...
to show
viviparity
In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juv ...
, or giving birth to live young.
Discovery and naming
The
holotype
A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
was found in the Kimberley area of northern
Western Australia
Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
by Lindsay Hatcher during the 2005 expedition to the Gogo led by
John Long of
Museum Victoria
Museums Victoria is an organisation that includes a number of museums and related bodies in Melbourne. These include Melbourne Museum, Immigration Museum, Scienceworks (Melbourne), Scienceworks, IMAX Melbourne, a research institute, the UNESCO W ...
. Fossils from the Gogo Formation are preserved in
limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
nodules, so dilute
acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
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 preserve ...
, often preserved in three dimensions with minimal distortion.
The species was named ''Materpiscis attenboroughi'' in honour of
David Attenborough
Sir David Frederick Attenborough (; born 8 May 1926) is an English broadcaster, biologist, natural historian and writer. He is best known for writing and presenting, in conjunction with the BBC Studios Natural History Unit, the nine nature d ...
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 sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
, where
male
Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual repro ...
s have clasping organs and
female
An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction.
A female has larger gametes than a male. Females and ...
s have smooth pelvic fin bases. It had long been suspected that they reproduced using
internal fertilisation, 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
Arizona State University (Arizona State or ASU) is a public university, public research university in Tempe, Arizona, United States. Founded in 1885 as Territorial Normal School by the 13th Arizona Territorial Legislature, the university is o ...
and an international committee of
taxonomists.
Pea-sized Seahorse, Bacteria That Life In Hairspray, Caffeine-free Coffee Among Top 10 New Species Of 2008 Science Daily May 23, 2009
/ref>
See also
*'' Austroptyctodus'', another viviparous ptyctodont placoderm from the Gogo Reef
*'' Incisoscutum'', a viviparous arthrodire
Arthrodira (Greek for "jointed neck") is an Order (biology), order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetratin ...
placoderm from the Gogo Reef
*'' Gogonasus''
*'' Onychodus''
* List of things named after David Attenborough and his works
References
{{Taxonbar, from=Q131787
Ptyctodontids
Gogo fauna
Fossil taxa described in 2008
Placoderm genera