- published: 31 Dec 2015
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Placodermi (from the Greek πλάξ = plate and δέρμα = skin, literally "plate-skinned") is an extinct class of armoured prehistoric fish, known from fossils, which lived from the Silurian to the end of the Devonian Period. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species. Placoderms were among the first jawed fish; their jaws likely evolved from the first of their gill arches. Placoderms are paraphyletic, and comprise several distinct outgroups or sister taxa to all living jawed vertebrates, which originated among their ranks. This is illustrated by a 419-million-year-old fossil, Entelognathus, from China, which is the only known placoderm with a type of bony jaw like that found in modern bony fishes. This includes a dentary bone, which is found in humans and other tetrapods,. The jaws in other placoderms were simplified and consisted of a single bone. Placoderms were also the first fish to develop pelvic fins, the precursor to hindlimbs in tetrapods, as well as true teeth. 380-million-year-old fossils of three other genera, Incistoscutum, Materpiscis and Austroptyctodus, represent the oldest known example of live birth.
The Devonian period (420 - 360 mya) is also known as the Age of Fishes as this was the time that fish became the dominant lifeform throughout the oceans of the world. Placodermi are an extinct class of armoured Paleozoic fish that were amongst the most successful and interesting creatures of this time. They are considered indirectly related to all living jawed vertebrates and are presumed to have been plentiful and mobile because their collective remains have been found right across the globe from Northern Europe to Southern Australia. Paleozoo represents a collection of anatomical models that looks at the structure of some of the earliest forms of life known to have existed on the planet.
I was given a class of animal (The Placodermi). It does not exist anymore in this world. :( So I recreated it with type then again in "real". enjoy
PLACODERMS_DINICHTHYS
By Marco Castiello Welcome to our coverage of Progressive Palaeontology, the Palaeontological Association’s conference for early-career academics, this year held at the University of Bristol, UK.
Today we examine the famous bony jawed placoderm fish from the Devonian, Dunkleosteus! We talk about everything from alternate universes, lips, and how you are related to these swimming bear traps! Prepare to learn about the Age of the Fishes and the bizarre fish that inhabited our oceans and could have taken over the Earth! Hope you enjoy! Sources: https://www.researchgate.net/publication/257074090_A_Silurian_placoderm_with_osteichthyan-like_marginal_jaw_bones http://www.nature.com/nature/journal/v491/n7426/fig_tab/nature11555_F2.html http://www.abc.net.au/science/articles/2015/06/24/4261003.htm http://www.nature.com/nature/journal/v502/n7470/fig_tab/nature12690_F1.html https://sites.google.com/a/pdx.edu/marek-rise-of-fish/ http://www.nature.com/nature/journal/v502/n7470/fig_tab/na...