Friday, June 30, 2017

[PaleoIchthyology • 2017] Scalacurvichthys naishi • A New Pycnodont Fish from the Late Cretaceous of Israel


Scalacurvithys naishi 
Cawley & Kriwet, 2017

Illustration: Ashley Patch plastospleen.deviantart.com 

Abstract

A new pycnodont fish from the early–mid Cenomanian, Late Cretaceous, of the ‘Ein Yabrud quarry near the village of Beit Eil in Israel is the first pycnodont fish to be described from this locality. Due to the locality where it was found, Scalacurvithys naishi gen. et sp. nov. is considered an inhabitant of reefal waters interspersed with lagoons in the eastern Tethys Sea. Scalacurvichthys naishi is notable for its protruding, hook-shaped first dorsal ridge scale above a large triangular dermatocranium, a deeply sloped and antero-posteriorly shortened skull and bifurcated cloacal scales. The bifurcating scales are a new character previously unknown in pycnodontomorph fishes but have been discovered in two more taxa, which indicates a new type of character that will be useful for future phylogenetic analyses of pycnodontomorph fishes. The new taxon is a member of Pycnodontidae and we conducted a phylogenetic analysis to establish its relationships to other pycnodont fishes. Our results reveal that Scalacurvichthys naishi is a well-resolved member of the subfamily Pycnodontinae.

Keywords: Tethys, Cenomanian, Pycnodontomorpha, phylogeny, morphology, taxonomy


Systematic palaeontology

Class Osteichthyes Huxley, 1880
Subclass Actinopterygii Cope, 1887

Series Neopterygii Regan, 1923 
Division Halecostomi Regan, 1923 sensu Patterson, 1973 

Order Pycnodontiformes Berg, 1937
Family Pycnodontidae sensu Nursall, 1996
cf. Subfamily Pycnodontinae Poyato-Ariza & Wenz, 2002 

Genus Scalacurvichthys gen. nov.

Type species: Scalacurvichthys naishi sp. nov.

Age: Early–middle Cenomanian, Late Cretaceous.

Diagnosis: Pycnodontid fish with the following autapomorphic characters: large triangular dermocranium; large anteriorly curved first dorsal ridge scale which protrudes above the skull roof; 11 dorsal axonosts; single post-cloacal ventral ridge scale; position of anal fin (preanal length/standard length) being at 70–79%; large, anterior and posterior bifurcating cloacal scales. Unique combination of plesiomorphic and derived characters: body outline intermediate between discoid and fusiform; body height 50% of standard length (SL); dermocranial fenestra absent; premaxillary bone with two teeth and no olfactory fenestra; 21 neural vertebrae excluding the caudal peduncle; 30–31 caudal fin rays; four epurals and 10 hypochordals in the caudal endoskeleton; hypochordals six, seven and eight seem to be fused into a large fan-shaped ossification.

Derivation of name: The genus name is derived from the Latin noun ‘scala’ meaning ‘scale’, the Latin adjective ‘curva’ meaning ‘curved’ in allusion to the raised, anterior-facing first dorsal ridge scale protruding above the skull roof, characteristic of this genus, and the Greek noun ‘ἰχθύς’ meaning ‘fish’.

Figure 1. A, Scalacurvichthys naishi  gen. et sp. nov., holotype (SMNK-PAL. 8613).
B, camera lucida drawing of Scalacurvichthys naishi gen. et sp. nov.; dashed lines indicate the restoration of incompletely preserved structures; bones shaded in grey are reconstructions while the rest of the drawing is the original specimen. Scale bars = 1 cm.
 

Scalacurvichthys naishi sp. nov.

Age: Bet Meir or the slightly younger Amminadava Formation, middle part of the Judea Group, early to middle Cenomanian, early Late Cretaceous.

Type locality: Limestone quarry near the village of Beit El, Binyamin Region, West Bank, Israel.

Stratigraphical range: Early–middle Cenomanian, Late Cretaceous.

Derivation of name: The name of the new species is dedicated to Dr Darren Naish who is currently writing a book on the entire vertebrate fossil record and is prolific in publishing research on dinosaurs, pterosaurs and marine reptiles amongst many other groups of tetrapods.


John J. Cawley and Jürgen Kriwet. 2017. A New Pycnodont Fish, Scalacurvichthys naishi gen. et sp. nov., from the Late Cretaceous of Israel. Journal of Systematic Palaeontology. Online edition.   DOI: 10.1080/14772019.2017.1330772


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