Pseudactinoceratidae
Encyclopedia
Pseudactinoceraidae is a family in the nautiloid cephalopod order, Pseudorthocerida
, known from the Upper Devonian and Lower Carboniferous
(Mississippian).
Pseuactinocerids are characterized by elongated, straight and gently curved shells with a subcentral siphuncle composed of broadly expanded segments in the adult in which there are internal deposits pieced by two series of radial canals. Deposits form initially at the septal openings and grow mostly forward to connect with the next deposit in the anterior part of the next segment. The radial canals connect the interior of the segments with the ends of the connecting rings as they approach adjacent septa. Camerae, which are generally short, are commonly filled with organic deposits.
Flower preferred the term Macroloxoceratidae, (ex Macrolooxcerainae, a subfamily in the Pseuorthoceratidae) which he proposed; reasoning that since Macroloxoceras
is based on an adult speciment and is better defined than Pseudactinoceras
which is based on a juvenile portion of a phagmocone, it is a better choice by which the (sub)family should be named.
Pseudorthocerida
Pseudorthocerida are generally straight longiconic nautiloids with a subcentral to marginal cyrtochoanitic siphuncle composed of variably expanded segments which may contain internal deposits that may develop into a continuous parietal lining.. Cameral deposits are common and concentrated ventrally...
, known from the Upper Devonian and Lower Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
(Mississippian).
Pseuactinocerids are characterized by elongated, straight and gently curved shells with a subcentral siphuncle composed of broadly expanded segments in the adult in which there are internal deposits pieced by two series of radial canals. Deposits form initially at the septal openings and grow mostly forward to connect with the next deposit in the anterior part of the next segment. The radial canals connect the interior of the segments with the ends of the connecting rings as they approach adjacent septa. Camerae, which are generally short, are commonly filled with organic deposits.
Flower preferred the term Macroloxoceratidae, (ex Macrolooxcerainae, a subfamily in the Pseuorthoceratidae) which he proposed; reasoning that since Macroloxoceras
Macroloxoceras
Macroloxoceras is a large pseuorthocerid from the upper Devonian of Central Colorado and Southern New Mexico with features resembling those found inactinocerids....
is based on an adult speciment and is better defined than Pseudactinoceras
Pseudactinoceras
Pseudactinoceras is an extinct nautiloid cephalopod included in the order Pseudorthocerida and the namesake of the family Pseudactinoceratidae .-Description:...
which is based on a juvenile portion of a phagmocone, it is a better choice by which the (sub)family should be named.