The Middle Eocene Belosaepia ungula (Cephalopoda: Coleoida) from Texas: structure, ontogeny and function

Abstract

The ontogeny of Belosaepia ungula Gabb, 1860 from the Crockett Formation (Bartonian stage, Eocene) of Texas is documented for growth from embryo to old age. During the last stage of life, much skeletal resorption occurred, resulting in a major change in form of the skeleton. the animal produced a large skeleton (to 180 mm in length and 50 mm in diameter) with endogastric coiling, oblique septa and a very large siphuncle. the skeleton has a guard with a solid posterior prong, a posteroventral corona plate and a noded dorsal shield. the ventral margin of the skeleton consists of a thin flattened deck containing strongly recurved septa, conotheca and a secondary prismatic shell layer. New terms are defined for features of the skeleton not previously described. the microstructure of the ventral deck and the presence of a rod structure between the prong and callus are described for the first time. Chamberlets similar to those in living Sepia cuttlebones are present between closely spaced septa and they vary from walled units on lateral margins to pillar form in mid-ventor. the siphuncle is secondarily thickened within the dorsal interior, producing a siphuncle band. the skeleton was produced by a deep-bodied animal of demersal life habits. the species B. uncinata, B. harrisi and B. alabamensis voltzi proposed by Palmer (1937) are synonymised with B. ungula. the species B. veatchii and B. saccaria of Palmer (1937) are considered to be valid species, but B. alabamensis proposed by Palmer (1937) is synonymised with B. veatchii. Descriptions of belosaepiid species must be based only on specimens of adult size that have not been affected by resorption.

A unique late Eocene coleoid cephalopod Mississaepia from Mississippi, USA: New data on cuttlebone morphology, ultrastructure, chemical composition, and their phylogenetic implications

“…Phrag− mocone structure and ultrastructure, and shell material composition in extinct sepiids is poorly known. Cuttlebone morphology of early ontogenetic stages was illustrated from Ceratisepia (Meyer 1993) and Belosaepia (Yancey et al 2010). A bimineralic, aragonite/calcite, composition of the cuttlebone was recently suggested for Anomalosaepia (Yancey and Garvie 2011).…”

Miocene sepiids (Cephalopoda, Coleoidea) from Australia

“…Belosaepiids migrated westwards (Košt'ák et al, 2013) and disappeared worldwide during the late Eocene: in North and South America (Weaver and Ciampaglio, 2003;Yancey et al, 2010) without descendent and in the Mediterranean with descendent, namely less-well-known sepiids like Archaeosepia Szörényi (late Eocene-late Oligocene), which are the root of advanced sepiids. Notosepia is also possibly a descendent of the Archaeosepia species group possessing a mosaic of primitive (e.g.…”

Seagrass and cuttlefish—an historic association

“…Belosepia proxima was recorded from glauconitic sandstone from Boekelo (Netherlands) (Bartonian, middle Eocene) in a molluscan fauna containing a lucinid (PDB 3718). Yancey et al (2010) described the ontogeny of Belosaepia ungula based on 160 individuals, mostly consisting of the strongly calcified posterior portion of the skeleton, from the Crockett Formation (Bartonian stage, middle Eocene) of Texas compared to similar aged material in Mississippi, Alabama and elsewhere in Texas. No information was available to judge on past seagrass presence.…”

“…Although generally rare, past cuttlefish records vary from single occurrences (McNamara and Kendrick, 1994;Gaudant et al, 2010;Lebrun et al, 2012), to many specimens (Weaver and Ciampaglio, 2003;Yancey et al, 2010;Košťák et al, 2016) and multispecies presence (Palmer, 1937;Palmer and Brann, 1965;Weaver and Ciampaglio, 2003;Košťák et al, 2016). In several cases there is evidence for cuttlefish and seagrass being present over several million years (Weaver et al, 2010b;Tracey et al, 1996).…”

“…Preservation of belosaepiids often consists of the strongly calcified posterior portion of the cuttlebone when hundreds of such fragments may be noted (Weaver and Ciampaglio, 2003;Yancey et al, 2010). Although also consisting of fragments, some Sepia are well preserved as cuttle bones (Košťák et al, 2016) with rare soft part preservation.…”