Takuya Konishi

University of Cincinnati | UC · Department of Biological Sciences

Mosasaurs (Squamata: Mosasauridae) were a highly diverse, globally distributed group of aquatic lizards in the Late Cretaceous (98–66 million years ago) that exhibited a high degree of adaptation to life in water. To date, despite their rich fossil record, the anatomy of complete mosasaur sclerotic rings, embedded in the sclera of the eyeball, has...

A specimen of a halisaurine mosasaur is reported from Japan for the first time, closing the pre-existing biogeographical gap between the Middle East and the eastern Pacific. Phosphorosaurus ponpetelegans sp. nov., from the lowermost Maastrichtian of Hokkaido, has been assigned to the genus Phosphorosaurus for sharing the following suite of major cr...

We here report on the smallest-known, neonate-sized Tylosaurus specimen, FHSM VP-14845, recovered from the lower Santonian portion of the Niobrara Chalk exposed in Kansas, U.S.A. Lacking any associated adult-sized material, FHSM VP-14845 comprises fragmentary and associated cranial bones, here considered to represent a single neonatal individual wi...

We examined the morphological diversity of the quadrate bone in squamate reptiles (i.e. lizards, snakes, amphisbaenians). The quadrate is the principal splanchnocranial element involved in suspending the lower jaw from the skull, and its shape is of particular interest because it is potentially affected by several factors, such as phylogenetic hist...

FHSM VP-5515 is a medium-sized russellosaurine mosasaur collected in the 1970s in Logan County, western Kan-sas, USA. A suite of cranial features are unique to this specimen at the species level. One is a conspicuous lack of a predental rostrum on the premaxilla, whose dentigerous portion is spatula shaped in dorsoventral aspect. Furthermore, the f...

We examined a selection of three-dimensionally preserved quadrate bones from representatives of all major clades of mosasauroid reptiles, an extinct group of marine lizards inclusive of aigialosaurs and mosasaurs (Squamata, Mosasauroidea). The quadrate bones appear to be very diverse within and across mosasauroid clades, and show variable combinati...

The Upper Cretaceous phosphates of Morocco preserve one of the world’s most diverse assemblages of mosasaurs, reflecting the adaptive radiation of this clade during the Maastrichtian. Herein, we describe a new mosasaur from these deposits. Although the teeth of this specimen resemble those of ‘Platecarpus’ ptychodon, suggesting referral to this spe...

A basal mosasauroid specimen, including a rib and a vertebra from the middle to posterior portion of the trunk, is reported from the lower Campanian Inoceramus (Platyceramus) japonicus Zone in Obira Town, northern Hokkaido, northern Japan. It is the second occurrence of basal mosasauroids sensu lato in Japan after the halisaurine Phosphorosaurus po...

Herein, we report an euselachian assemblage from the late Campanian Bearpaw Formation recovered from southern Alberta, Canada. This small yet uniquely diverse fauna includes the northern-most occurrences of Paraorthacodus andersoni, Squalus worlandensis, Odontaspis aculeatus, and Archaeotriakis ornatus within the Western Interior Seaway. It also co...

UALVP 40, an articulated and reasonably complete skull of a small chasmosaurine dinosaur collected in 1920 by George F. Sternberg from the lower unit of the Dinosaur Park Formation, Dinosaur Provincial Park, Alberta, Canada, is here redescribed. The focus of the study is on the newly prepared right side of the skull and the hitherto undescribed man...

A new aulopiform, Ursichthys longiparietalis, gen. et sp. nov., preserved within and around the body cavity of a mosasaur, Mosasaurus missouriensis, is described from the Bearpaw Formation (upper Campanian, ca. 74.8 Ma) of Alberta, Canada (paleolatitude = 57 degrees N). The partial skeleton consists of a partial skull associated with other isolated...

A new, exquisitely preserved specimen of a small mosasaur, referable to Mosasaurus missouriensis, is reported from the Bearpaw Formation (ca. 75 Ma, upper Campanian) of southern Alberta, Canada. Many calcified cartilaginous elements, including tracheal rings and the sternum, are preserved. The sternum most closely resembles that of Clidastes propyt...

LACM 128319, which was collected in western Kansas, U.S.A., and is assignable to Platecarpus tympaniticus (Mosasauridae, Plioplatecarpinae), represents arguably one of the most exquisite mosasaur specimens known to date. Measuring 5.67 m from the tip of the snout to the end of the tail, it comprises an exceptionally well-articulated skeleton, accom...

Taxonomy and stratigraphic distribution of the Upper Cretaceous marine reptiles from Japan are reviewed. Remains of the Chelonioidea (sea turtles), Mosasauridae, and Plesiosauria are known in various parts of Japan, including the holotypes of the dermochelyid Mesodermochelys undulatus, mosasaurine Mosasaurus hobetsuensis and M. prismaticus, tylosau...

The marine reptile Prognathodon (Squamata: Mosasauridae), a mosasaurine mosasaur exhibiting a characteristically robust skull and dentition, lived during the last two ages of the Late Cretaceous. Fossilized remains of animals assigned to this genus are so far known from North America, Europe, Africa, and New Zealand, indicating their wide geographi...

A jaw fragment of a large mosasaurine (Squamata, Mosasauridae) was discovered from the uppermost Cretaceous Izumi Group in Sennan City, Osaka Prefecture, Southwest Japan as a concretionary float. While the specimen is fragmentary, three complete and one partial alveoli are preserved, the anteriormost one being largest. The third alveolus contains a...

Currently known from the early Campanian to late Maastrichtian, Prognathodon constitutes a group of mosasaurine mosasaurs that typically possessed massive jaws. Only four articulated skulls are known to date and the information concerning their postcrania remains minimal. Moreover, the early to middle Campanian specimens of the taxon are extremely...

A new plioplatecarpine taxon, Latoplatecarpus, gen. nov., is proposed here to incorporate two species, L. willistoni, sp. nov., and L. nichollsae (comb. nov.). The new genus is currently restricted in distribution to the lower middle Campanian of North America. Phylogenetic analysis incorporating 97 morphological characters and 17 ingroup taxa indi...

The fragmentary holotype and only known material of Platecarpus tympaniticus Cope, 18698. Cope , E. D. 1869. On the reptilian orders, Pythonomorpha and Streptosauria. Boston Society of Natural History Proceedings, 12: 250–266. View all references, is redescribed and compared to other closely related plioplatecarpine mosasaurs. Re-characterization...

Measurements of dorsal and ventral centrum length (in mm) at the tailbend, in thirteen caudals that precede the bend and in thirteen caudals that succeed it. (0.01 MB XLS)

Mosasaurs (family Mosasauridae) are a diverse group of secondarily aquatic lizards that radiated into marine environments during the Late Cretaceous (98-65 million years ago). For the most part, they have been considered to be simple anguilliform swimmers--i.e., their propulsive force was generated by means of lateral undulations incorporating the...

A new species of the basal tylosaurine mosasaur Taniwhasaurus, is described from materials collected from upper Santonian-lower Campanian marine clastics outcropping near Mikasa City, Island of Hokkaido, Japan. The type species, Taniwhasaurus oweni Hector, 1874, was originally described from a partial frontal and right and left dentaries collected...

One of the most enigmatic species of North American mosasaur, Platecarpus planifrons (Upper Coniacian—Lower Santonian), is re-diagnosed based on reference to the holotype, a new and very well-preserved skull (UALVP 24240), and several other less complete specimens. P. planifrons, once considered a nomen vanum, is diagnosed by a number of characters...