Cryptolithinid trilobites have been repeatedly described from North America for over 150 years. Earlier work on these forms is here integrated with new information from Oklahoma to form a strong case for the following conclusions: 1) the genus Cryptolithus migrated to (present-day) eastern North America from Europe at a single time in the early Caradoc; 2) it gave rise rapidly to a western North American relative, Cryptolithoides; 3) both genera were restricted to relatively cool-water shelf environments roughly 30 m deep and remained, in general, geographically isolated for several million years. The Viola Group, geographically between these eastern and western occurrences and representing much of Middle and Upper Ordovician time, chronicles the interplay between these two genera over some six million years.

In the biogeographic boundary region formed by Oklahoma, the two supposedly distinct genera showed suprising convergence of fringe pit and other character traits as marine transgression reduced provinciality through Ordovician time. This suprising convergence of genera is interpreted as hybridization of mere subspecies after several million years of incomplete geographic separation.

The Lower–Middle Ordovician (Ibexian, Whiterockian) sedimentary rocks exposed at Rancho Las Norias includes the informally named Las Norias formation, which consists of an intercalation of carbonate and clastic sediments with abundant marine fauna. These deposits occur as the most austral sedimentary rocks of Ordovician age for Laurentia, providing a critical link to understand the distribution of Ordovician marine faunas of North America. An investigation of the gastropod fauna from the upper portion of the Las Norias formation, Sonora, Mexico, is undertaken for the first time. The gastropod assemblage includes Maclurites acuminatus, ?Monitorella sp., Lecanospira sp., Malayaspira aff. M. rugosa, Lophospira perangulata, and Hormotoma? sp. This assemblage indicates a paleogeographic relationship with Laurentia, including the USA (Nevada), Canada (British Columbia, Newfoundland), Greenland, and the Argentine Precordillera.

A new genus and species of obolellid brachiopod, Brevipelta chouberti, is described from the Early Cambrian of Morocco. It is a useful index fossil for the upper Choubertella Zone and the Daguinaspis Zone in Morocco. Additionally discussed are taphonomic aspects that lead to the question whether the shell may have been weakly calcified compared to other obolellid brachiopods and the calcareous part may have been composed of aragonite crystallites, or whether the preservation of Brevipelta is due to facile solubility of a calcitic shell substance. Brevipelta chouberti represents not only the oldest described Early Cambrian brachiopod from Africa, but one of the oldest obolellid brachiopods known worldwide.

Juvenile specimens of the Paleocene–Eocene pantodont Coryphodon provide more extensive ontogenetic information for this genus than is available for other Paleocene–Eocene mammals. The dental eruption sequence for Coryphodon is: 1) (DC11, DI1–31–3); 2) DP44; 3) DP33; 4) DP22; 5) (M11, I33); 6) DP11, 7) M22; 8) P44; 9) P33; 10) (P22, I11?); 11) C11; 12) (M33, I22) (eruption sequence of tooth positions in parentheses is uncertain). The DP11 of Coryphodon do not have permanent successors. No significant, qualitative morphological variation can be detected in deciduous cheek teeth of Coryphodon, and metric analysis of these teeth failed to detect taxonomically significant differences. The ontogenetically youngest Coryphodon is known from parts of a skeleton of an individual perhaps less than three years old at the time of death. This skeleton and other partial juvenile skeletons suggest that juvenile Coryphodon grew quickly and approached near-adult proportions before the deciduous dentition was lost or the epiphyses of the long bones began to fuse.

Lower Miocene rocks of the uppermost part of the Pysht Formation and the overlying Clallam Formation on the Olympic Peninsula, Washington have yielded rare fossils of a small crab, Cancer (Metacarcinus) starri, new species. This is the second lower Miocene record of the genus Cancer and the oldest of the subgenus Metacarcinus.

Specimens of the gastropod genus Donaldina are numerous throughout marine units of the Pottsville, Allegheny, and Conemaugh Groups in the Appalachian Basin. Six species of Donaldina from thirteen marine units are described. New species proposed are Donaldina quadroliratus, from Pottsville and Allegheny units, and Donaldina superclivis, from Conemaugh units.

A new species of the Pliocene–Pleistocene flat-headed peccary, Platygonus pollenae, has been recovered latest Hemphillian (latest Miocene) localities from Nebraska, Kansas, Colorado, and Texas. It can be distinguished from other tayassuids by its distally rounded wing-like zygomatic process, and its subzygodont cheek teeth. In contrast to more derived species of Platygonus, it is much smaller in size, its molars are relatively more bunodont, the talon and talonid cusps are retained on the premolars of most individuals, and the mandibular symphysis lacks a median keel on the chin. In these characters, it is the earliest and the most primitive species of Platygonus known. It is more primitive than the typical Blancan species, or any of the species from the Pleistocene, and demonstrates the origin of this important Pleistocene mammal in the latest Miocene.

The latest Ordovician to earliest Silurian graptolite Avitograptus avitus is important in the biostratigraphy of the Ordovician–Silurian boundary interval. Two additional species of Avitograptus are described from the sponge-dominated Anji Biota of the Upper Ordovician Wenchang Formation (Metabolograptus persculptus Biozone) of Zhejiang Province, South China. One species, Avitograptus akidomorphus new species, is new; the other, Avitograptus acanthocystus new combination, which was previously placed in Climacograptus, is herein assigned to Avitograptus. The former species may represent the ancestral akidograptid because it is identical in thecal form to Akidograptus, but differs in the development of the proximal end. The evolutionary changes from Avitograptus avitus to Akidograptus and Parakidograptus involved distal movement of the origins of th11 and th12, thecal elongation, and greater outward inclination of the thecal walls.

UUID: http://zoobank.org/81c433a0-9069-48d2-ae72-1267400cbf77.

A new species of Megacerops, M. kuwagatarhinus, is described from deposits belonging to the White River Group in southeastern Montana. Megacerops kuwagatarhinus is distinguished from all other species of Megacerops by the peculiar morphology of the horns, which are bifurcated distally into two well-developed branches. Two specimens from the Hunter Quarry of Saskatchewan, Canada, also share this horn morphology and are referred to the species.

A lower molar of a new species of rodent, Prosciurus? shantungensis, from the subsurface of eastern China adds to the diversity of the known Asian prosciurine aplodontids and increases the likelihood that aplodontids were widespread in Eurasia during the Oligocene. This form is structurally close to the North American prosciurine aplodontids, especially Prosciurus relictus from the middle Oligocene. The metaconid is strongly compressed and reduced in height, a condition partially developed in P. relictus but here more extreme. Height of the mesoconid and the degree of lophodonty are more advanced than in North American species of Prosciurus. P.? shantungensis differs from the prosciurine-like lower dentitions from Kazakhstan and Mongolia described by Argyropulo (1939) and Kowalski (1974) in crest development and in details of the cusp morphology. Types of the Asian prosciurine or presumed prosciurine species are upper dentitions for which associated lower dentitions are unknown, yet the slope of the crests in Prosciurus lohiculus is too low to match the occlusal surface in P.? shantungensis and the degree of lophodonty in P. arboraptus is less than would be expected for the upper dentition of the Shantung form.

The level of colony integration in tabulate corals is the degree of colony unity with respect to behavior, physiology, and development of individual organs or organ complexes within colonies. These are difficult to assess in fossils, but the level of colony integration can be tested by analyzing ontogenies and astogenies of two common Paleozoic tabulate coral groups, favositids and heliolitids. Favositids have been previously interpreted as highly integrated colonies, but results of the present examination suggest that the level of colony integration in favositids was rather lower than hitherto assumed. The ontogenies and astogenies in favositid colonies are not correlatable; thus, the significance of ontogenetic and astogenetic variations for systematic and phylogenetic resolution in favositids is difficult to assess at present. In contrast, astogenetic developmental sequences are recognized in heliolitids. Ontogenies in heliolitids were subordinated to the astogeny of the colony. This is closely related to the high degree of colony integration with respect to behavior and physiology of individual organs or organ complexes within colonies. Individual corallites were well linked and coordinated so that the whole colony could have functioned as a single individual. As a result, evolution in heliolitids operated at the colony level and by heterochronic (and other) modifications of astogenies rather than of ontogenies.

A new species of teuthid squid, Teudopsis cadominensis, is described from the Toarcian (Lower Jurassic) Poker Chip Shale of the Fernie Formation in central-western Alberta. Fossil squids are rare in the Mesozoic of North America; this species is the first record of the family Palaeololiginidae in North America and the first member of the suborder Mesoteuthina in the Jurassic of North America.

Eight new species of the conodont Neogondolella are described from the Anisian (Middle Triassic) of northeastern British Columbia. The subtlety of morphological variation in this conodont genus has hampered biostratigraphical correlation, but large, often independently dated collections have enabled the description of N. cuneiforme, N. curva, N. hastata, N. dilacerata, N. indicta, N. panlaurentia, N. tenera, and N. vellicata n. spp. Several of these species are widespread, as specimens of N. curva, N. hastata, N. indicta, N. panlaurentia, N. tenera, and N. vellicata are found in contemporary collections from Nevada, whereas N. panlaurentia has also been recovered from the Canadian Arctic. This distribution promises to significantly improve correlation among Anisian sections in North America.

Two orthothecid genera, Bolitheca n. gen. (type species Orthotheca steinmanni Knod, 1908) and Neobactrotheca n. gen. (type species Neobactrotheca pharetra n. sp.) are described from Bolivian rocks of Emsian and Eifelian age. Two incomplete and poorly preserved hyolithids are also described, one tentatively assigned to the family Pauxillitidae. Because so few specimens are known, it is not possible to compare Bolivian Devonian hyoliths with faunas from other regions, which are also poorly known.

The middle part of the Santa Rosita Formation (Tremadocian) is well exposed in the Iruya area, northwestern Argentina. At the Pantipampa and Rodeo Colorado localities, it is composed of shale and sandstone representing a wave-dominated shelf with influence of storm activity. Twenty-two trilobite species are described from these localities. Low-diversity assemblages from the lower part of the succession (Kainella meridionalis Kobayashi, Asaphellus catamarcensis Kobayashi, Leptoplastides marianus [Hoek]) are diagnostic of the early Tremadocian Kainella meridionalis Zone. Trilobites from the middle part of the sequence are much more diverse. Kainella teiichii Vaccari and Waisfeld, Gymnagnostus kobayashii n. sp., Conophrys sp. indet., Asaphellus clarksoni n. sp., A. stenorhachis (Harrington), A. isabelae Meroi Arcerito, Waisfeld and Balseiro, Ogygiocaris? iruyensis n. sp., Niobe (Niobella) inflecta (Harrington and Leanza) n. comb., Metayuepingia riccardii n. sp., Pseudokainella keideli Harrington, Apatokephalus rugosus n. sp., Onychopyge acenolazai n. sp., O. gonzalezae n. sp., Nileus cingolanii n. sp., N. erici n. sp., Leptoplastides marianus, Parabolinella sp. indet., Hapalopleura sp. indet., and Ceratopygidae gen. et sp. indet., occur at different levels of the Kainella teiichii Zone. This biostratigraphic unit includes the oldest records of Nileus Dalman and Ogygiocaris? Angelin; Metayuepingia Liu, Niobe (Niobella) Reed, and Onychopyge Harrington are here first reported from the Tremadocian of southwest Gondwana. Finally, the uppermost part of the succession is characterized by the absence of the genus Kainella Walcott and the occurrence of Bienvillia tetragonalis (Harrington), Asaphellus stenorhachis, Pseudokainella keideli and Leptoplastides sp. indet., which are indicative of the middle Tremadocian Bienvillia tetragonalis Zone. The trilobites described in this paper provide a basis for the refinement of correlations with other Lower Ordovician sections of the Cordillera Oriental. The genera recognized have their closest affinities with faunas from Scandinavia, Great Britain, and China.

A large, edrioasteroid-bearing hardground surface from the base of the Bellevue Member of the Grant Lake Formation near Maysville, Mason County, Kentucky is described. Four species are represented including Streptaster vorticellatus (Hall), Carneyella ulrichi Bassler and Shideler, Carneyella pilea (Hall), and Curvitriordo stecki n. sp. Specimens of S. vorticellatus and C. pilea add little to the known morphologies of these species. However, prior to this study C. ulrichi was known from the unique holotype, and Curvitriordo stecki n. sp. adds greatly to out understanding of Curvitriordo which was previously known from two species comprising three poorly preserved specimens. Curvitriordo stecki shows a bimodal size frequency distribution suggesting seasonal breeding whereas Carneyella ulrichi shows a left skewed size frequency suggesting low juvenile mortality. Streptaster vorticellatus shows a tight unimodal size frequency distribution suggestive of a single spat fall accumulation.

Cretaceous bryozoans from western North America are very poorly known. This paper describes twelve species of cheilostomes from the Upper Cretaceous of southern California and Baja California. the only previously described bryozoan, Ceriocava eastoni Woollacott, 1966, from the Holz Member (?Turonian-Campanian), Ladd Formation of the Santa Ana Mountains, is transferred from Cyclostomata to Cheilostomata, made the type species of the new genus Zimmerella and placed in the family Chiplonarinidae. the following new Campanian-Maastrichtian species are described from the Rosario, Point Loma, and Cabrillo formations of San Diego County, California and Le Misión, Baja California: Wilbertopora sannerae sp. nov., Onychocella schopforum sp. nov., Trichinopolia californica sp. nov., and T. lata sp. nov.

A new echinoderm fauna is reported from the Brassfield Formation (Rhuddanian, Silurian) of Bath County, Kentucky. The Brassfield Formation was the first extensive marine unit to be deposited following the end-Ordovician glaciation and extinctions and represents several shallow, open-marine facies. These facies supported a diverse pelmatozoan fauna. This report not only extends the geographic distribution of this fauna, but also the temporal range of the fauna back to Rhuddanian time. Six pelmatozoans are reported, including the crinoids Browerocrinus arthrikos n. gen. n. sp., Temnocrinus americanus n. sp., Stereoaster sp., and Dendrocrinus sp.; and the glyptocystitids Brockocystis nodosarius Foerste, 1919, and Anartiocystis whitei Sumrall, 2002. In addition, the asteroid Gordonaster brassfieldensis Blake and Ettensohn, 2009, was reported previously from this locality. Browerocrinus increases the diverse calceocrinid fauna from the Brassfield Formation; Temnocrinus was previously only known from the Homerian (Silurian) of England; and this is the first known occurrence of Stereoaster beyond the greater Dayton, Ohio, region. Furthermore, this is the first Brassfield locality known with two glyptocystitid taxa.

Based on the type material and a new, virtually intact skull from the mid-Maastrichtian part (probably Tierra Loma Shale) of the Moreno Formation, San Joaquin Valley, central California, the cranial osteology of the enigmatic mosasaurine Plesiotylosaurus crassidens (Squamata, Mosasauridae) is here described in detail. Plesiotylosaurus is characterized by a protruding rostrum on the snout and mandibles, a wide and virtually unconstricted internarial bar, large and robust pterygoid teeth, and quadrates with distally fused suprastapedial and infrastapedial processes. Distinctly obtruding predental prows, along with a number of elaborate cranial features, suggest a morphological convergence with tylosaurine mosasaurs.

Trochotomidae is a small but distinctive extinct family of pleurotomarioidean gastropods characterized by trochiform shells with an elliptical trema. Two new species of trochotomids are described from Pliensbachian deposits in the Neuquén Basin, Argentina. The new genus-group name Placotoma is proposed to replace the pre-occupied name Discotoma Haber non Mulsant. The record of Trochotoma (Trochotoma) protonotialis new species and Trochotoma (Placotoma) neuquensis new species in the early Jurassic of Argentina extends the paleobiogeographical distribution of the genus (and the family) to the Southern Hemisphere. The new taxa reported here represent a component of the pleurotomarioidean adaptive radiation that took place in the Tethyan region during the earliest Jurassic. They are related to local patch coral reefs of shallow, open-marine paleoenvironments, agreeing with the known habitat of most species of this family. The group was well represented in the Tethyan region during the Mesozoic, especially during the Jurassic, and the new species represent its southernmost occurrence.