Megalograptus is a four-foot long Ordovician eurypterid, and was among the earliest known genera. Its name means "big writing." It was named so because the first fossils were of its immensely spiny legs, were mistaken for massive graptolites. It lived from 460 to 445 mya. Megalograptus preyed on fish, trilobites, other sea scorpions, and smaller orthocones with the exception of adult Cameroceras. Though Megalograptus didn't have a stinger, it did curl its tail and sword-like telson foward as a threat pose, much like a scorpion. The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... The conservation status of a species is an indicator of the likelihood of that species continuing to survive either in the present day or the future. ... An ammonite fossil Eocene fossil fish of the genus Knightia Petrified wood fossil formed through permineralization. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Subregnum Parazoa Porifera Subregnum Eumetazoa Placozoa Orthonectida Rhombozoa Radiata (unranked) Ctenophora Cnidaria Bilateria (unranked) Acoelomorpha Myxozoa Superphylum Deuterostomia Chordata Hemichordata Echinodermata Chaetognatha Xenoturbellida Superphylum Ecdysozoa Kinorhyncha Loricifera Priapulida Nematoda Nematomorpha Onychophora Tardigrada Arthropoda Superphylum Platyzoa Platyhelminthes Gastrotricha Rotifera Acanthocephala Gnathostomulida Micrognathozoa Cycliophora Superphylum Lophotrochozoa Sipuncula Nemertea Phoronida Ectoprocta Bryozoa... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - Trilobites (extinct) Subphylum Chelicerata Arachnida - Spiders, Scorpions, etc. ... Orders many, all extinct The eurypterids were the largest known arthropods that ever lived. ... The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... Orders many, all extinct The eurypterids were the largest known arthropods that ever lived. ... For other senses of this word, see leg (disambiguation). ... Graptolites (Graptolithina) are fossil colonial animals known chiefly from the Upper Cambrian through the Mississippian (Lower Carboniferous). ... In astronomy, geology, and paleontology, mya is an acronym for million years ago and is used as a unit of time to denote length of time before the present. ... Orders Agnostida Redlichiida Corynexochida Lichida Nektaspida? Phacopida Proetida Asaphida Harpetida Ptychopariida Trilobites are extinct arthropods in the class Trilobita. ... An orthocone is a usually long straight shell of a nautiloid cephalopod. ... Species  ?  ?  ?  ? Cameroceras (chambered horn) was an 36 foot long orthocone that lived in the Ordovician. ... The telson is the last division of the body of a crustacean. ...

It was featured in the Ordovician episode of the BBC's Sea Monsters series, where they were imagined to have behaved similiarly to horseshoe crabs, coming to shore to breed and lay eggs in the surf and sand. The British Broadcasting Corporation, invariably known as the BBC (and also informally known as the Beeb or Auntie) is the largest broadcasting corporation in the world, employing 26,000 staff in the UK alone and with a budget of £4 billion. ... Sea Monsters was a BBC television program which used computer-generated imagery to show past life in Earths seas. ... Binomial name Limulus polyphemus Linnaeus, 1758 The horseshoe crab (Limulus polyphemus) is a chelicerate arthropod, therefore it is more closely related to spiders and scorpions than crabs. ...