{"id":976,"date":"2013-10-21T14:49:10","date_gmt":"2013-10-21T18:49:10","guid":{"rendered":"http:\/\/www.ordovicianatlas.org\/?page_id=976"},"modified":"2016-08-26T12:34:03","modified_gmt":"2016-08-26T16:34:03","slug":"phacopida","status":"publish","type":"page","link":"https:\/\/www.ordovicianatlas.org\/atlas\/arthropoda\/trilobita\/phacopida\/","title":{"rendered":"Phacopida"},"content":{"rendered":"
Classification<\/strong> Geologic Range<\/strong> Common Paleoecology<\/strong> Characteristics of the Order<\/strong><\/p>\n Calymenidae<\/p>\n
\nPhylum: Arthropoda<\/a>
\nClass: Trilobita<\/a>
\nOrder: Phacopida (Salter, 1853)
\nCincinnatian Families: Calymenidae<\/a>, Cheiruridae<\/a><\/p>\n
\nLower Ordovician (Arenig) – Middle Devonian<\/p>\n
\nPhacopida is an extinct order of fast-moving, low-level epifaunal carnivores.<\/p>\n\n
\nTreatise on Invertebrate Paleontology (1959):<\/em><\/p>\n\n
An order of post-Cambrian trilobites probably derived from the Ptychopariida. Cephalon with facial sutures typically proparian (most Phacopina and Cheirurina) or gonatoparian (most Calymenina, some Cheirurina), but may be opisthoparian (some Calymenina and Cheirurina) or even lacking (some Cheirurina); glabella variously shaped, commonly expanding forward (Phacopina, most Cheirurina) or tapering forward (Calymenina, some Cheirurina), lateral glabellar furrows (if present) variously developed; preglabellar field short (sag.) or lacking; rostral plate present (Calymenina, most Cheirurina) or lacking (Phacopina, some Cheirurina). Thorax with 8 to 19 segments. Pygidium mostly medium to large, but small in some exceptional early representatives. Known protaspides of similar type.<\/ul>\n<\/li>\n
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