Materpiscis is a small armored fish from the Devonian. Materpiscis would have been about 11 inches (28 cm) 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 fish. The ptyctodontid fish are the only group of placoderms to display sexual dimorphism, where males have clasping organs and females have smooth pelvic fin bases. It had long been suspected that they reproduced using internal fertilization, but finding fossilised embryos inside both Materpiscis and in a similar form also from Gogo, Austroptyctodus, proved the deduction was true. These results has hypothesis that Materpiscis gave birth to live young and take care of it until the child is big enough to go out on its own.