Bisonocerida is an order of Ordovician to Siluriannautiloidcephalopods. Members of this order were originally placed in the order Endocerida, but later investigation argued that this broad usage of Endocerida was a polyphyletic assemblage encompassing two different groups of independent origin. Bisonocerida was differentiated from Endocerida in 2012 in order to resolve this issue.[1]
Bisonocerids are similar to endocerids in many respects. The siphuncle was broad and positioned ventrally in the shell, which ranged in shape from cyrtoconic brevicones (curved and short) to rare orthoconic longicones (straight and long). The inner surface of the siphuncle contains endosiphuncular deposits, which help distinguish the two orders. In both bisonocerids and endocerids, the endosiphuncular deposits are conical in shape ("endocones"), concreted from the rim of the siphuncle and tapering towards the apex of the shell. Both orders possess simple perforate endocones, with a hole at the tip of each cone for siphuncle tissue to pass through. Structures similar to simple endocones are also apparently present in some members of the earlier cephalopod orders Yanhecerida and Ellesmerocerida.[1]
Unlike true endocerids, the simple endocones of bisonocerids are interlaced with a more complex form of endocone. “Complex” endocones are imperforate, without a hole at the tip. In cross-section, they are composed of several bulbous calcareous crests extending into the siphuncle. This only leaves an irregular and discontinuous pinched space, known as an infula, for the remaining siphuncle tissue. The infula may be compressed to the point that it resembles radiating splinters in cross-section, known as endosiphoblades. The calcareous crests were able to form by concreting onto narrow sheets of infolded conchiolin, a condition unique to bisonocerids.[1]
Other distinctive traits of bisonocerids include long septal necks and a siphuncle which is swollen at the apex of the shell. Bisonocerids appear to be oncomyarian, meaning that they have a numerous small, undifferentiated muscle scars ringing around their body chamber. This is unlike endocerids, which have a few large muscle scars at the top of the body chamber, a dorsomyarian condition.[1]
When originally defined as a new order, Bisonocerida was suggested to be an independent descendant of Ellesmerocerida.[1] It was later allied with the broad subclass Multiceratoidea.[2] However, a 2022 phylogenetic analysis argued that Bisonocerida was closely related to Endocerida once more. Under this hypothesis, the two orders were sister taxa within the subclass Endoceratoidea.[3]
Referencesedit
^ abcdeEvans, David H.; King, Andrew H. (2012-01-01). "Resolving polyphyly within the Endocerida: The Bisonocerida nov., a new order of early palaeozoic nautiloids". Geobios. 45 (1): 19–28. doi:10.1016/j.geobios.2011.11.015. ISSN 0016-6995.
^King, Andy H.; Evans, David H. (2019). "High-level classification of the nautiloid cephalopods: a proposal for the revision of the Treatise Part K". Swiss Journal of Palaeontology. 138 (1): 65–85. doi:10.1007/s13358-019-00186-4. ISSN 1664-2384. S2CID 133647555.
^Pohle, Alexander; Kröger, Björn; Warnock, Rachel C. M.; King, Andy H.; Evans, David H.; Aubrechtová, Martina; Cichowolski, Marcela; Fang, Xiang; Klug, Christian (2022-04-14). "Early cephalopod evolution clarified through Bayesian phylogenetic inference". BMC Biology. 20 (1): 88. doi:10.1186/s12915-022-01284-5. ISSN 1741-7007. PMC9008929. PMID 35421982.
January 01, 1970
bisonocerida, order, ordovician, silurian, nautiloid, cephalopods, members, this, order, were, originally, placed, order, endocerida, later, investigation, argued, that, this, broad, usage, endocerida, polyphyletic, assemblage, encompassing, different, groups,. Bisonocerida is an order of Ordovician to Silurian nautiloid cephalopods Members of this order were originally placed in the order Endocerida but later investigation argued that this broad usage of Endocerida was a polyphyletic assemblage encompassing two different groups of independent origin Bisonocerida was differentiated from Endocerida in 2012 in order to resolve this issue 1 BisonoceridaTemporal range Tremadocian Wenlock PreꞒ Ꞓ O S D C P T J K Pg N Cassinoceras a Floian piloceratid Scientific classification Domain Eukaryota Kingdom Animalia Phylum Mollusca Class Cephalopoda Subclass Nautiloidea Superorder Endoceratoidea Order BisonoceridaEvans amp King 2012 Families Allotrioceratidae Bisonoceratidae Chihlioceratidae Coreanoceratidae Emmonsoceratidae Humeoceratidae Manchuroceratidae Najaceratidae Piloceratidae Proterovaginoceratidae Sinoendoceratidae Bisonocerids are similar to endocerids in many respects The siphuncle was broad and positioned ventrally in the shell which ranged in shape from cyrtoconic brevicones curved and short to rare orthoconic longicones straight and long The inner surface of the siphuncle contains endosiphuncular deposits which help distinguish the two orders In both bisonocerids and endocerids the endosiphuncular deposits are conical in shape endocones concreted from the rim of the siphuncle and tapering towards the apex of the shell Both orders possess simple perforate endocones with a hole at the tip of each cone for siphuncle tissue to pass through Structures similar to simple endocones are also apparently present in some members of the earlier cephalopod orders Yanhecerida and Ellesmerocerida 1 Unlike true endocerids the simple endocones of bisonocerids are interlaced with a more complex form of endocone Complex endocones are imperforate without a hole at the tip In cross section they are composed of several bulbous calcareous crests extending into the siphuncle This only leaves an irregular and discontinuous pinched space known as an infula for the remaining siphuncle tissue The infula may be compressed to the point that it resembles radiating splinters in cross section known as endosiphoblades The calcareous crests were able to form by concreting onto narrow sheets of infolded conchiolin a condition unique to bisonocerids 1 Other distinctive traits of bisonocerids include long septal necks and a siphuncle which is swollen at the apex of the shell Bisonocerids appear to be oncomyarian meaning that they have a numerous small undifferentiated muscle scars ringing around their body chamber This is unlike endocerids which have a few large muscle scars at the top of the body chamber a dorsomyarian condition 1 When originally defined as a new order Bisonocerida was suggested to be an independent descendant of Ellesmerocerida 1 It was later allied with the broad subclass Multiceratoidea 2 However a 2022 phylogenetic analysis argued that Bisonocerida was closely related to Endocerida once more Under this hypothesis the two orders were sister taxa within the subclass Endoceratoidea 3 References edit a b c d e Evans David H King Andrew H 2012 01 01 Resolving polyphyly within the Endocerida The Bisonocerida nov a new order of early palaeozoic nautiloids Geobios 45 1 19 28 doi 10 1016 j geobios 2011 11 015 ISSN 0016 6995 King Andy H Evans David H 2019 High level classification of the nautiloid cephalopods a proposal for the revision of the Treatise Part K Swiss Journal of Palaeontology 138 1 65 85 doi 10 1007 s13358 019 00186 4 ISSN 1664 2384 S2CID 133647555 Pohle Alexander Kroger Bjorn Warnock Rachel C M King Andy H Evans David H Aubrechtova Martina Cichowolski Marcela Fang Xiang Klug Christian 2022 04 14 Early cephalopod evolution clarified through Bayesian phylogenetic inference BMC Biology 20 1 88 doi 10 1186 s12915 022 01284 5 ISSN 1741 7007 PMC 9008929 PMID 35421982 Retrieved from https en wikipedia org w index php title Bisonocerida amp oldid 1188096997, wikipedia, wiki, book, books, library,
