Michael G. Newbrey

A partial skeleton of the Late Cretaceous lamniform shark, Archaeolamna kopingensis, from the Pierre Shale of western Kansas, U.S.A.

ABSTRACT All previous records of the lamniform shark, Archaeolamna kopingensis, are based on isolated teeth. Here we describe a partial skeleton from the Sharon Springs Formation of the Pierre Shale Group of western Kansas, U.S.A. The specimen includes portions of the upper and lower jaws with articulated teeth. The dentition consists of two files of upper and lower anterior teeth that, together with a single file of intrabullar intermediate teeth, are housed in a dental bulla, as well as multiple files of lateral teeth, along with at least two files of lower symphysial teeth and a single file of upper symphysial teeth. The intrabullar intermediate tooth is slightly shorter than the other anterior teeth and has a median cusp with distinctive distal curvature. The dental sequence of A. kopingensis is unique among both extinct and extant lamniforms. Associated with the jaws are fragments of the neurocranium and multiple vertebral centra. A sagittal section through a centrum shows that this shark deposited 18 annual marker bands after its birth and adult size was attained by the 10th band. The robust but penetrating tooth morphology and large jaw circumference suggest that A. kopingensis likely fed upon large prey items.

A new articulated freshwater fish (Clupeomorpha, Ellimmichthyiformes) from the Horseshoe Canyon Formation, Maastrichtian, of Alberta, CanadaThis article is one of a series of papers published in this Special Issue on the theme Albertosaurus.

Horseshoeichthys armaserratus, gen. et sp. nov., (Clupeomorpha: Ellimmichthyiformes: Sorbinichthyidae) is described from the Horseshoe Canyon Formation (Maastrichtian), Albertosaurus bonebed locality, Alberta, Canada. Horseshoeichthys armaserratus is classified as an ellimmichthyiform based on the following characters: the presence of a sixth infraorbital with a sensory canal that leads to the fifth infraorbital, absence of a supraorbital bone, subrectangular predorsal scutes, parietals in contact with each other at the midline, and two supramaxillae. The specimen is classified in the Sorbinichthyidae Family as it has abdominal ribs articulating in pits on the centra, posterior spines on predorsal scutes, and absence of a median spine on predorsal scutes. A new genus and species is proposed based on the presence of (anteriorly) Y-shaped mesethmoid, supraorbital, subrectangular predorsal scutes with coarse, rounded serrae on the posterior margin and a large anterior projection, scales with serrae on the ci...

Cenomanian—Campanian (Late Cretaceous) Mid-Palaeolatitude Sharks of Cretalamna appendiculata Type

The type species of the extinct lamniform genus Cretalamna, C. appendiculata, has been assigned a 50 Ma range (Albian—Ypresian) by a majority of previous authors. Analysis of a partly articulated dentition of a Cretalamna from the Smoky Hill Chalk, Kansas, USA (LACM 128126) and isolated teeth of the genus from Cenomanian to Campanian strata of Western Australia, France, Sweden, and the Western Interior of North America, indicates that the name of the type species, as applied to fossil material over the last 50 years, represents a large species complex. The middle Cenomanian part of the Gearle Siltstone, Western Australia, yielded C. catoxodon sp. nov. and “Cretalamna” gunsoni. The latter, reassigned to the new genus Kenolamna, shares several dental features with the Paleocene Palaeocarcharodon. Early Turonian strata in France produced the type species C. appendiculata, C. deschutteri sp. nov., and C. gertericorum sp. nov. Cretalamna teeth from the late Coniacian part of the Smoky Hill Chalk in Kansas are assigned to C. ewelli sp. nov., whereas LACM 128126, of latest Santonian or earliest Campanian age, is designated as holotype of C. hattini sp. nov. Early Campanian deposits in Sweden yielded C. borealis and C. sarcoportheta sp. nov. A previous reconstruction of the dentition of LACM 128126 includes a posteriorly situated upper lateroposterior tooth, with a distally curved cusp, demonstrably misplaced as a reduced upper “intermediate” tooth. As originally reconstructed, the dentition resembled that of cretoxyrhinids (sensu stricto) and lamnids. Tooth morphology, however, indicates an otodontid affinity for Cretalamna. The root is typically the most diagnostic feature on an isolated Cretalamna tooth. This porous structure is commonly abraded and/or corroded and, consequently, many collected Cretalamna teeth are indeterminable at species level.

A small, exquisitely preserved specimen of Mosasaurus missouriensis (Squamata, Mosasauridae) from the upper Campanian of the Bearpaw Formation, western Canada, and the first stomach contents for the genus

ABSTRACT 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 propython, bearing five shallow sternal rib facets on each side. Our comparative study of the new material with the holotype, referred material, and the genotype M. hoffmannii is congruent with the preexisting hypothesis that M. missouriensis and M. hoffmannii are phylogenetically more closely related to each other than to the other congeners, in spite of a temporal gap of nearly 10 million years between them. Also preserved with the mosasaur, inside its ribcage and around the specimen, are well-preserved aulopiform fish bones, including a skull. The fish skull is punctured and its centra truncated, suggesting macrophagy was employed by M. missouriensis despite the apparent lack of tooth wear. A sympatric specimen of Prognathodon overtoni is known to have consumed a sea turtle as well as fishes, and consistently exhibits apical wear across marginal teeth. We hypothesize that coexistence of these apex predators in the Bearpaw Sea was possible because of niche partitioning. Finally, the mosasaur carcass was likely scavenged by at least three lamniform sharks, based on their shed teeth and a series of truncated transverse processes on the mosasaur tail.

Seventy-five-million-year-old tropical tetra-like fish from Canada tracks Cretaceous global warming

Newly discovered fossil fish material from the Cretaceous Dinosaur Park Formation of Alberta, Canada, documents the presence of a tropical fish in this northern area about 75 million years ago (Ma). The living relatives of this fossil fish, members of the Characiformes including the piranha and neon tetras, are restricted to tropical and subtropical regions, being limited in their distribution by colder temperatures. Although characiform fossils are known from Cretaceous through to Cenozoic deposits, none has been reported previously from North America. The modern distribution of characiforms in Mexico and southern Texas in the southernmost United States is believed to have been the result of a relatively recent colonization less than 12 Ma. The new Canadian fossils document the presence of these fish in North America in the Late Cretaceous, a time of significantly warmer global temperatures than now. Global cooling after this time apparently extirpated them from the northern areas and these fishes only survived in more southern climes. The lack of early Cenozoic characiform fossils in North America suggests that marine barriers prevented recolonization during warmer times, unlike in Europe where Eocene characiform fossils occur during times of global warmth.

A high latitude euselachian assemblage from the early Turonian of Alberta, Canada

Numerous isolated euselachian teeth were recovered from the early Turonian Kaskapau Formation situated in northwestern Alberta, Canada. This high palaeolatitude assemblage was collected from a sandstone lens along the bank of the Smoky River, and includes 16 species belonging to at least three orders, at least 11 families, and 15 genera. Here we describe Odontaspis watinensis sp. nov. and report the first Canadian occurrence of Polyacrodus sp., Scapanorhynchus sp., and Carcharias aff. C. striatula. The scarcity of benthic taxa in this assemblage supports the previous notion that bottom waters in this region of the Western Interior Seaway experienced enduring anoxic episodes. By comparing the faunal composition of this assemblage with that of middle Cenomanian Canadian assemblages, we show that seven species have a biostratigraphical range that extended across the Cenomanian–Turonian boundary in the northern region of the seaway. Of the taxa described herein, Archaeolamna ex. gr. kopingensis, Cardabiodon aff. C. ricki, Carcharias aff. C. striatula, Odontaspis watinensis, and Johnlongia parvidens have not been reported from deposits of the southernmost region of the seaway and may have been restricted to cooler waters. http://zoobank.org/urn:lsid:zoobank.org:pub:FD671818-2769-484C-B424-F5EF5490A6A9

The first record of the large Cretaceous lamniform shark, Cardabiodon ricki, from North America and a new empirical test for its presumed antitropical distribution

ABSTRACT The first occurrence of the lamniform Cardabiodon ricki is reported from the late Cenomanian of Alberta, Canada. Previously, this taxon was described from Australia and Europe and has been hypothesized in the published literature as having an antitropical distribution. Whereas the occurrence of C. ricki in Alberta seemingly supports this hypothesis, no formal methodology exists to determine if Cardabiodon had an antitropical distribution because sampling for Cenomanian fossil elasmobranchs in the tropics is poor. We offer a novel methodology to test the purported hypothesis of an antitropical distribution for Cardabiodon by examining three paleoecological aspects. We compare the range of sea surface temperatures (SST) and paleolatitudinal ranges of Cardabiodon localities to those of the extant antitropical shark, Lamna nasus, because Cardabiodon should exhibit a similar magnitude of thermal and paleolatitudinal ranges to those of L. nasus. Furthermore, the paleodistribution of Cardabiodon localities should shift with climate change. Cardabiodon is concluded to have an antitropical distribution because (1) the SST range for Cardabiodon was only slightly greater (by 1.7°C) than that recorded for L. nasus; (2) the difference in paleolatitude range for Cardabiodon was 10° latitude less than the modern range for L. nasus; and (3) the paleolatitudes of Cardabiodon localities are positively correlated with global temperature to indicate that, during warm periods, Cardabiodon was found at higher paleolatitudes in both hemispheres, but it was found at warmer, lower latitudes during cooler periods.

AGE, GROWTH, AND MORTALITY OF JOFFRICHTHYS TRIANGULPTERUS (TELEOSTEI: OSTEOGLOSSIDAE) FROM THE PALEOCENE SENTINEL BUTTE FORMATION, NORTH DAKOTA, U.S.A

Abstract Fossilized Joffrichthys triangulpterus scales collected from an ancient lake site in the Paleocene Sentinel Butte Formation near Almont, North Dakota, provide an opportunity to estimate growth, natural mortality, and survival for this species. Based on 166 J. triangulpterus scales, fish ages ranged from zero through nine years old. Four scale-covered skeletons were also recovered and aged at zero, zero, one, and four years of life. Based on an age-frequency histogram, age groups zero, one, and two are clearly under-represented at the Almont site, suggesting they likely inhabited different areas of the lake system, perhaps due to habitat partitioning between juveniles and adults in the lake. Instantaneous natural mortality (M) determined from age-frequency data indicates the average annual mortality of age three and older J. triangulpterus was –0.456 (r2 = 0.958), which is similar to numerous extant fish mortality curves. A Von Bertalanffy growth curve (r2 = 0.977) indicates that growth of J. triangulpterus was rapid in the first three years of life, attaining over 70% of their adult size before reaching an asymptote in growth at age nine. The maximum body size attained by one individual of J. triangulpterus was estimated at 316 mm total length. The growth pattern and mortality rates exhibited in J. triangulpterus are generally similar to those of numerous extant fish taxa found in temperate latitudes.

New articulated osteoglossomorph from Late Cretaceous freshwater deposits (Maastrichtian, Scollard Formation) of Alberta, Canada

ABSTRACT Articulated fishes are rare in Late Cretaceous non-marine deposits of the Western Interior; fishes are more often represented by disarticulated elements in vertebrate microfossil localities. A new Maastrichtian locality of the Scollard Formation in central Alberta, Canada, has been named Pisces Point to reflect the diversity of articulated fishes that are now being recovered from this site. Material collected from the Pisces Point locality includes a percopsiform, a semionotiform, at least one esociform, and at least two osteoglossomorphs. One of these is described here as a new genus and species, †Wilsonichthys aridinsulensis. A phylogenetic analysis shows this new taxon to be the sister group of most other Osteoglossiformes. The new articulated material allows us to identify some of the microfossil remains previously collected from other Late Cretaceous sites as belonging to the same or a similar taxon.

Vertebral Morphology, Dentition, Age, Growth, and Ecology of the Large Lamniform Shark Cardabiodon ricki

Cardabiodon ricki and Cardabiodon venator were large lamniform sharks with a patchy but global distribution in the Cenomanian and Turonian. Their teeth are generally rare and skeletal elements are less common. The centra of Cardabiodon ricki can be distinguished from those of other lamniforms by their unique combination of characteristics: medium length, round articulating outline with a very thick corpus calcareum, a corpus calcareum with a laterally flat rim, robust radial lamellae, thick radial lamellae that occur in low density, concentric lamellae absent, small circular or subovate pores concentrated next to each corpus calcareum, and papillose circular ridges on the surface of the corpus calcareum. The large diameter and robustness of the centra of two examined specimens suggest that Cardabiodon was large, had a rigid vertebral column, and was a fast swimmer. The sectioned corpora calcarea show both individuals deposited 13 bands (assumed to represent annual increments) after the birth ring. The identification of the birth ring is supported in the holotype of Cardabiodon ricki as the back-calculated tooth size at age 0 is nearly equal to the size of the smallest known isolated tooth of this species. The birth ring size (5–6.6 mm radial distance [RD]) overlaps with that of Archaeolamna kopingensis (5.4 mm RD) and the range of variation of Cretoxyrhina mantelli (6–11.6 mm RD) from the Smoky Hill Chalk, Niobrara Formation. The revised, reconstructed lower jaw dentition of the holotype of Cardabiodon ricki contains four anterior and 12 lateroposterior files. Total body length is estimated at 5.5 m based on 746 mm lower jaw bite circumference reconstructed from associated teeth of the holotype.