Inside modern P. hemioliopterus brand new involved central area of the skull roof is practically entirely ornamented by the reticulating ridges and you may pits, having partners or no elongate, synchronous ridges and you may sulci ( Fig. 4a). Throughout the Acre Phractocephalus brand new main side of the head roof has some elongate ridges and sulci in addition to reticulating ridges and you will pits.
This new lateral ethmoid bones out-of P
2) Mesethmoid bones really wider ( Dining table 1); dorsal epidermis commonly ornamented; anterior boundary barely emarginate so you’re able to lightly game ( Fig. 3a).
The new mesethmoid bone away from P. hemioliopterus is fairly thin-necked, less widely ornamented merely centrally and you may posteriorly, and its particular prior boundary was emarginate otherwise shallowly concave ( Fig. 4a). nassi.
3) Horizontal ethmoid not excessive projecting anteriorly more than palatine condyle; the lateral margin convex and you can removing orbital notch on the margin regarding skull rooftop ( Fig. 3a).
hemioliopterus is even maybe not excessively projecting anteriorly across the olfactory region or palatine condyle; however it is concave laterally, possesses a well discussed orbital sulcus towards the margin from head roof ( Fig. 4a). Regarding Acre Phractocephalus the brand new horizontal ethmoid ideas much anteriorly more the new olfactory area and you will palatine condyle; it is convex sideways, removing the orbital sulcus on the margin out-of skull roof.
Modern P. hemioliopterus keeps an open anterior cranial fontanelle within this popular despair out of epiphyseal region ( Fig. 4a), while in the Acre Phractocephalus brand new fontanelle and you will despair of the epiphyseal part lack.
5) Supraoccipital procedure which have circular lateral and you can posterolateral margins, posterior margin concave medially; supraoccipital processes a lot of time, in the dorsal see completely level modified prior spinal vertebrae out-of Weberian cutting-edge ( Fig. 3a).
The fresh opercle P
During the modern P. hemioliopterus the newest supraoccipital procedure is actually brief, inside dorsal evaluate maybe not completely layer modified spinal vertebrae off Weberian state-of-the-art; it’s angular horizontal and you may posterolateral margins, and its own posterior margin try abnormal so you can concave medially and you may affect a deep unornamented extension less than anterior nuchal plate ( Fig. 4a). Throughout the Acre Phractocephalus the new supraoccipital techniques is much time, completely covering the Weberian advanced; the processes has angular corners and you will upright horizontal margins, and its particular posterior ented extension lower than anterior nuchal dish.
hemioliopterus was incompletely wrapped in reticulating ridges and you may pits ( Fig. 5c). Brand new opercle was at this point unknown on the Acre Phractocephalus.
7) Cleithrum that have rough ornamentation extending along ventral line forming external pouch or “shoulder” horizontal in order to lower back articulation; fat off “shoulder” terminating posteriorly, in line with cancellation from articular outlet out-of pectoral spine ( Figs. 5e-g).
Brand new cleithrum from P. hemioliopterus lacks coarse ornamentation with each other ventral edge of “neck,” in addition to horizontal bulge from “shoulder” terminates rear to the level out-of articular retailer out-of pectoral lower back ( Figs. 5i, j). No cleithrum of the Acre Phractocephalus has been found.
8) Pectoral spine ornamentation reigned over from the rough subparallel ridges and you will sulci, and you can seemingly couple reticulating ridges and you can pits ( Fig. 5h).
The fresh pectoral spine ornamentation off P. hemioliopterus was ruled by the reticulating ridges and pits ( Fig. 5i). The pectoral lower back of your Acre Phractocephalus are but really unfamiliar.
Etymology. The fresh new Urumaco species of Phractocephalus is called having Dr. Pedro Nass in detection out-of his benefits toward systematics and morphology regarding pimelodid catfishes out of South america.
Dysfunction. Come across Lundberg et al. (1988) to own breakdown regarding neurocranium (MCN.USB 72-85 PB) and extra proportions. The following data is available with the new holotype and recently obtained specimens.
Neurocranium, dorsal factor ( Fig. 3a). Outline particular skull approximately rectangular, thickness across horizontal ethmoids equal to thickness around the sphenotics, and these widths slightly lower than restriction thickness round the pterotic wings; thickness across the pterotics contains dos.25 times inside the (45% of) dorsal head size from mesethmoid suggestion in order to rear edge of supraoccipital process. Skin generally flat however, margins curved slightly downwards and you may dorsal midline much more arched posteriorly. All the skeleton ornamented with rough reticulating ridges and you can circular pits and some longitudinally elongate ridges and you may grooves, apart from olfactory capsules and you will extremities out-of mesethmoid cornua.