Inside the modern P. hemioliopterus the involved central region of the skull rooftop is practically entirely ornamented of the reticulating ridges and you can pits, that have partners if any elongate, synchronous ridges and sulci ( Fig. 4a). In the Acre Phractocephalus brand new main area of the skull rooftop has many elongate ridges and you can sulci as well as reticulating ridges and you may pits.
The fresh horizontal ethmoid bone from P
2) Mesethmoid bone most wide ( Table step one); dorsal epidermis widely ornamented; anterior boundary barely emarginate so you can gently round ( Fig. 3a).
The mesethmoid limbs of P. hemioliopterus is fairly narrow-necked, shorter extensively ornamented only centrally and posteriorly, and its particular prior line are emarginate or shallowly concave ( Fig. 4a). nassi.
3) Lateral ethmoid not excessive projecting anteriorly more palatine condyle; their horizontal margin convex and eliminating orbital notch towards the margin off head rooftop ( Fig. 3a).
hemioliopterus is additionally not a lot of projecting anteriorly across the olfactory region or palatine condyle; however it is concave laterally, possesses a properly laid out orbital sulcus for the margin off skull rooftop ( Fig. 4a). Regarding Acre Phractocephalus the horizontal ethmoid programs much anteriorly more this new olfactory region and you may palatine condyle; it is convex laterally, getting rid of the fresh orbital sulcus towards margin off head rooftop.
Modern P. hemioliopterus has actually an open prior cranial fontanelle inside a prominent depression away from epiphyseal area ( Fig. 4a), whereas about Acre Phractocephalus the latest fontanelle and you will despair of your own epiphyseal area lack.
5) Supraoccipital processes that have circular lateral and posterolateral margins, posterior margin concave medially; supraoccipital procedure a lot of time, into the dorsal examine totally level changed anterior backbone out of Weberian complex ( Fig. 3a).
This new opercle P
In modern P. hemioliopterus the latest supraoccipital processes is brief, into the dorsal look at perhaps not completely coating altered vertebrae out of Weberian state-of-the-art; it has got angular horizontal and you will posterolateral margins, and its particular rear margin are unpredictable so you can concave medially and hit a deep unornamented expansion lower than anterior nuchal dish ( Fig. 4a). On the Acre Phractocephalus the fresh new supraoccipital techniques was much time, completely within the Weberian advanced; its process enjoys angular sides and straight lateral margins, and its rear ented extension lower than prior nuchal dish.
hemioliopterus is actually incompletely covered with reticulating ridges and pits ( Fig. 5c). The opercle is actually up to now unknown on the Acre Phractocephalus.
7) Cleithrum having rough ornamentation extending with each other ventral line developing outward pouch or “shoulder” lateral to spine articulation; pouch away from “shoulder” terminating posteriorly, in line with cancellation out of articular socket off pectoral back ( Figs. 5e-g).
The fresh cleithrum of P. hemioliopterus lacks rough ornamentation with each other ventral side of “neck,” while the horizontal bulge regarding “shoulder” terminates posterior to the stage out of articular outlet off pectoral spine ( Figs. 5i, j). Zero cleithrum of Acre Phractocephalus is known.
8) Pectoral lower back ornamentation reigned over from the coarse subparallel ridges and sulci, and seemingly couple reticulating ridges and pits ( Fig. 5h).
This new pectoral spine ornamentation off P. hemioliopterus was dominated by reticulating ridges and you will pits ( Fig. 5i). The brand new pectoral spine of your Acre Phractocephalus is yet www.datingmentor.org/escort/seattle , unknown.
Etymology. The Urumaco species of Phractocephalus is called getting Dr. Pedro Nass in recognition from his efforts for the systematics and you may morphology off pimelodid catfishes from South america.
Breakdown. Discover Lundberg et al. (1988) getting malfunction off neurocranium (MCN.USB 72-85 PB) and extra measurements. The following information is provided with the brand new holotype and you will recently gotten specimens.
Neurocranium, dorsal factor ( Fig. 3a). Story sorts of skull everything square, width all over horizontal ethmoids equivalent to depth all over sphenotics, that widths a little less than limit thickness around the pterotic wings; thickness across the pterotics contained 2.twenty five minutes within the (45% of) dorsal head size off mesethmoid tip to help you posterior edge of supraoccipital procedure. Facial skin primarily flat but margins curved slightly down and you may dorsal midline all the more arched posteriorly. Most of the bones ornamented having coarse reticulating ridges and rounded pits and you can certain longitudinally elongate ridges and you can grooves, with the exception of olfactory medications and you may extremities of mesethmoid cornua.
Recent Comments