Kritosaurus navajovius skeletal morphology

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com


A new online paper:


Albert Prieto-Márquez (2013)
Skeletal morphology of Kritosaurus navajovius (Dinosauria:
Hadrosauridae) from the Late Cretaceous of the North American
south-west, with an evaluation of the phylogenetic systematics and
biogeography of Kritosaurini.
Journal of Systematic Palaeontology (advance online publication)
DOI:10.1080/14772019.2013.770417
http://www.tandfonline.com/doi/full/10.1080/14772019.2013.770417#.UYyURLXvtcQ


The osteology of the hadrosaurid dinosaur Kritosaurus navajovius (late
Campanian of southern North America) is documented in detail, and the
taxonomy and phylogenetic relationships of the genus are revised.
Kritosaurus is rediagnosed based on the extensive length of the
dorsolateral margin of the maxilla and a unique combination of
characters that includes a jugal with orbital constriction deeper than
infratemporal one, infratemporal fenestra greater than orbit and with
dorsal margin greatly elevated above dorsal orbital margin in adults,
frontal participating in orbital margin, and paired caudal
parasagittal processes of nasals resting over frontals. The taxonomy
of numerous hadrosaurid specimens previously referred to Kritosaurus
is reassessed; the vast majority of these cannot be positively
referred to Kritosaurus. One exception is a specimen collected from
the Cerro del Pueblo Formation that extends the geographical range of
K. navajovius further south in Laramidia, to present-day northern
Mexico. Anasazisaurus is regarded a junior synonym of Kritosaurus;
their holotypes are indistinguishable from each other when considering
the overlapping elements. However, many characters support distinction
of Naashoibitosaurus ostromi as a valid taxon. Kritosaurus, consisting
of the sister species K. navajovius and K. horneri, is deeply nested
within Saurolophinae as a member of Kritosaurini. The latter clade
includes also Naashoibitosaurus, Gryposaurus, and the South American
Secernosaurus. Kritosaurini is characterized by a rostral nasal dorsal
process not reaching the rostral margin of the narial foramen, frontal
with triangular rostrolateral projection ending in a narrow apex
(convergent in Brachylophosaurini), and a subrectangular dorsal region
of infratemporal fenestra, among other characters. Kritosaurin
hadrosaurids are hypothesized to have originated in southern Laramidia
no later than the early Campanian. Subsequently, members of the clade
reached northern Laramidia and South America via dispersal no later
than the early and late Campanian, respectively.