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Macroloxoceras
''Macroloxoceras'' is a large pseuorthocerid from the upper Devonian of Central Colorado and Southern New Mexico with features resembling those found in
actinocerids.〔Macroloxoceras, a Devonian Homeomorph of the Actinoceratida, part II Memoir 2, Studies of the Actinoceatidae by Rousseau H Flower. New Mexico Bureau of Mines and Mineral Resources, Socorro NM 1957〕
Pseudorthocerids and actinocerids (respectively Pseuorthocerida and Actinocerida) are extinct nautiloid cephalopods, generally with long straight shells and expanded siphuncle segments filled with organic deposits.
==Morphologic Description==
''Macroloxoceras'' has an orthconic shell with a strongly depressed cross section and markedly flattened venter. Sutures have broad ventral lobes but are otherwise straight and transverse. The siphuncle is ventral of the center; composed of broadly expanded segments with a spheroidal outline. Septal necks are cytochoantic. Connecting rings are thin and make contact over a wide area on the previous septa at their adapical ends. Endosiphuncular deposits are fairly ubiquitous, begin at the septal openings and grow mostly forward to connect with the next in the anterior part of the following segment. Cavities left in the segments are connected to the rings by two series of radial canals; one at the anterior end of the segment near the end of the septal neck; the other starting in the middle, curving back and ending about where the connecting rings makes contact with the previous septum. Cameral deposits are well developed.〔〔Nautiloidea-Orthocerida by Walter C Sweet, Treatise on Invertebrate Paleontology Part K Mollusca 3, R.C Moore (ed) 1964〕
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