A new species of sturgeon (Acipenseridae), †Psammorhynchus longipinnis n. gen. and sp., is described based on a single well-preserved specimen from the Upper Cretaceous Judith River Formation of Montana. Although based on only a single individual, the osteological detail we are able to describe for this species is extensive because of the completeness of the specimen, the relatively three-dimensional preservation, and the soft, loosely consolidated sandstone matrix in which it was contained (allowing some dissection of the specimen to reveal the internal bones of the head region). We prepared the specimen completely out of the matrix, and described the head region in stages of “dissection.” †Psammorhynchus longipinnis is the only fossil sturgeon to date that provides a relatively complete, reliable look at its osteology. Although there have previously been numerous and widespread reports of fossil sturgeons, the material is notoriously fragmentary and poorly preserved, consisting mostly of isolated scutes or pectoral spines (summarized here in an appendix) and it is of very limited use to phylogenetic studies of living sturgeon taxa. The only other described articulated skeleton of a fossil sturgeon is †Protoscaphirhynchus squamosus Wilimovsky from the Upper Cretaceous Hell Creek Formation of Montana. That specimen (the only one known for the species) is a badly preserved, very poorly prepared skeleton showing little detail of the head region. It is interesting to note that the only known articulated fossil sturgeon skeletons (†Psammorhynchus longipinnis n. gen. and sp.; †Protoscaphirhynchus squamosus Wilimovsky; and a third, yet undescribed specimen) were apparently each independently discovered in the abdominal regions of hadrosaurian dinosaurs (as was the Cretaceous paddlefish †Paleopsephurus wilsoni MacAlpin). Perhaps hadrosaur carcasses provided the right combination of taphonomic factors to protect acipenseriform carcasses from damage in high energy aquatic environments predominantly preferred by sturgeons. In any case, based on known specimens, sediments within hadrosaurs appear to have been the main preservational medium for articulated fossil sturgeon skeletons in North America.

†Psammorhynchus longipinnis appears to be the sister taxon to the rest of Acipenseridae based on our preliminary analysis here. We will reevaluate this relationship elsewhere in our (Hilton, Grande, and Bemis) ongoing study of fossil and living Acipenseridae.

A pleurodontan iguanian from the Green River Formation (Eocene) is described in detail and named. The new taxon is known only from a single specimen preserving all areas of the body. Although many of the bone surfaces are eroded, almost all of the skeleton is present and some cartilaginous elements are preserved. The new taxon shares important characteristics with the extant anisolepines and leiosaurines, including the morphology and placement of the caudal autotomy planes, the postxiphisternal inscriptional ribs, and notched or fenestrated clavicles that are expanded proximally. This is the earliest complete iguanian known from the Americas and the earliest known iguanian that may be confidently referred to an extant “family.” A phylogenetic analysis including this taxon and other fossil and extant iguanians offers some support for the monophyly of Polychrotidae sensu lato, Tropiduridae sensu lato, and non-acrodont iguanians (Pleurodonta).

Tubular specimens belonging to Hyolithellus from silty dolostones of the basal Aftenstjernesø Formation of North Greenland may represent the first occurrence of this widespread Cambrian fossil in life position. A high proportion of preserved specimens are oriented normal to bedding with the tapering end of the tube down. Occasional undulations in the growth of the tubes indicate that the animal actively adjusted its growth to achieve a vertical orientation in relation to the sediment surface. Increasing thickness of the tube wall towards the tapering end shifted the center of mass downwards and resulted in greater stability in the sediment. The tube remained open at both ends throughout ontogeny; it was most likely secreted by an annelid-grade animal which pumped water into the sediment through the tube. Hyolithellus and similar tubular fossils from the Lower Cambrian probably represent stem group annelids.

Ediacaran trace fossils are becoming an increasingly less common component of the total Precambrian fossil record as structures previously interpreted as trace fossils are reinterpreted as body fossils by utilizing qualitative criteria. Two morphotypes, Form E and Form F of Glaessner (1969), interpreted as trace fossils from the Ediacara Member of the Rawnsley Quartzite in South Australia are shown here to be body fossils of a single, previously unidentified tubular constructional morphology formally described herein as Somatohelix sinuosus n. gen. n. sp. S. sinuosus is 2-7 mm wide and 3-14 cm long and is preserved as sinusoidal casts and molds on the base of beds. Well-preserved examples of this fossil preserve distinct body fossil traits such as folding, current alignment, and potential attachment to holdfasts. Nearly 200 specimens of this fossil have been documented from reconstructed bedding surfaces within the Ediacara Member. When viewed in isolated hand sample, many of these specimens resemble ichnofossils. However, the ability to view large quantities of reassembled and successive bedding surfaces within specific outcrops of the Ediacara Member provides a new perspective, revealing that isolated specimens of rectilinear grooves on bed bases are not trace fossils but are poorly preserved specimens of S. sinuosus. Variation in the quality and style of preservation of S. sinuosus on a single surface and the few distinct characteristics preserved within this relatively indistinct fossil also provides the necessary data required to define a taphonomic gradient for this fossil. Armed with this information, structures which have been problematic in the past can now be confidently identified as S. sinuosus based on morphological criteria. This suggests that the original organism that produced this fossil was a widespread and abundant component of the Ediacaran ecosystem.

A new specimen of Bohaiornis guoi from the Jiufotang Formation, comprising a nearly complete skeleton, sheds light on enantiornithine morphological variation and ecological specialization. The new specimen was collected from near Lamadong Village in Liaoning Province, which is the same area where the sub-adult holotype specimen was reported. It provides new information on the cranial and pectoral girdle anatomy of the species, e.g., broad nasal, strikingly robust acromion, medially curved acrocoracoid process. In contrast to the holotype, the newly referred specimen has small rounded stones in the thoracic region that in other extinct taxa has been interpreted as direct evidence of diet. Direct evidence of diet is so far unknown in other Enantiornithes. Specifically the lack of “stomach stones” or gastroliths in enantiornithines despite their excellent fossil record has been proposed to be related to their insectivorous diet as well as to their arboreal ecology. We hypothesize that cranial morphology as well as the number and shape of the preserved stones in Bohaiornis may be most consistent with a raptorial ecology previously unknown for Enantiornithes and considered rare for Avialae. While rostrum shape has a strong relationship to feeding ecology in living birds, in basal avialan birds most diversity is in dental morphology, number, and distribution of the teeth.

Hexactinosidan sponges are important reef-building organisms in Earth history as they are able to create a three-dimensional reef framework and thereby form topographic relief comparable to that produced by scleractinian corals. Study of modern hexactinosidan sponge skeletons from water depths of 165–240 m on the continental shelf off British Columbia, Canada, demonstrate the hitherto undescribed frame-building process that leads to the formation of large and so far unique siliceous sponge reefs in this area. The fundamentals of the frame-building process are based on the production of siliceous envelopes around spicules of dead hexactinosidan sponges. In addition to the development of a three-dimensional reef framework, mound growth is supported by the current baffling effect of the sponges. Fine-grained siliciclastic suspended sediment is trapped and deposited within the gaps in the sponge skeletons and in voids in the reef surface preventing the framework from collapsing as the reef grows.

Analogous but tropical examples from the Lower Jurassic of Portugal show that the frame-building potential of hexactinosidan and other siliceous sponges has existed, substantially unchanged, for more than 180 million years. In contrast to well-known fossil mud mounds of various geologic ages, in which the in situ precipitation of automicrite via microbial processes plays a major role, the matrix of the hexactinosidan sponge mounds of British Columbia consists exclusively of baffled fine-grained siliciclastics; automicrite is absent. Existing mud mound classification schemes do not encompass these depositional characteristics, therefore this new type of mound is consequently here classified as a silicate mound.

Erosion of the upper Arkadelphia Formation by the Ouachita River in Hot Spring County, Arkansas, has revealed a diverse and abundant, late Maastrichtian chondrichthyan fauna representing at least 17 species: Squatina hassei, Ginglymostoma lehneri, Plicatoscyllium derameei, Ondontaspis aculeatus, Carcharias cf. C. holmdelensis, Serratolamna serrata, Squalicorax kaupi, Galeorhinus girardoti, Rhinobatos casieri, Ischyrhiza avonicola, Ischyrhiza mira, Sclerorhynchus sp., Ptychotrygon cf. P. vermiculata, Raja farishi, Rhombodus binkhorsti, and Dasyatis sp. All of these species are widely known from the Upper Cretaceous of North America. An extremely rare species, Schizorhiza cf. S. stromeri, currently known only from Mexico and Africa, is also present. The chondrichthyan remains occur almost entirely as teeth scattered by river activity across the surface of the marl and marly clay of the Arkadelphia Formation and can be collected from within localized accumulations of river sediments. Also present with the chondrichthyan remains are teeth from actinopterygians and reptiles as well as molluscan steinkerns, echinoid spines, and fragments of branching corals. This fauna expands the known geographic distribution of late Maastrichtian chondrichthyans in North America, and provides an important biostratigraphic connection between fauna of the Gulf Coastal Plain and Western Interior Seaway. It also supports the idea of a significant chondrichthyan turnover across the Cretaceous–Tertiary boundary.

Estimates of Precambrian eukaryotic diversity and disparity indicate broad trends of increase in the Mesoproterozoic Era, leading to a peak and then rapid decline by ca. 750 Ma. The organic-walled microfossil assemblage presented here is representative of that mid-Neoproterozoic height of eukaryotic species richness. Organic-rich shales and siltstones of the mid-Neoproterozoic upper Alinya Formation, eastern Officer Basin, Australia, preserve an abundant and diverse assemblage of organic-walled microfossils deposited in a low-latitude, shallow marine setting. Use of scanning electron microscopy (SEM) revealed an unexpected level of morphological detail not visible in transmitted light microscopy. This led to the recognition of new species as well as establishment of degradational sequences, which aid in fossil recognition. In total, 26 taxa are described here; these include 21 previously named forms, four newly described species (Caelatimurus foveolatus, Culcitulisphaera revelata, Karenagare alinyaensis, and Morgensternia officerensis), and one new combination (Vidalopalla verrucata).

A new centrosaurine ceratopsid, Albertaceratops nesmoi, is described from the lower Oldman Formation (Upper Cretaceous) of southern Alberta, and is based on a single, almost complete skull. Referred material is described from equivalent beds in the Judith River Formation of north-central Montana. A limited phylogenetic analysis of the Ceratopsidae places the new taxon as the basal member of the Centrosaurinae and indicates that robust, elongate postorbital horncores that form a synapomorphy of (Ceratopsidae + Zuniceratops) are also present in Centrosaurinae.

Tikisuchus romeri n. gen. and sp. is a rauisuchid thecodontian from the Late Triassic Tiki Formation of India and is the first rauisuchid material to be recorded from Asia. The skull is very large in relation to the presacral length and is equipped with sharp, serrated teeth. The astragalus has a very high dorsal process and the calcaneal tuber is short; the ankle joint is of “crocodile-normal” type.

The rauisuchids were the dominant terrestrial predators during the Triassic and shared similar ecological niches with the emerging theropods. The agility and superior locomotion of theropods may have contributed to their success and to their eventual replacement of the rauisuchids at the end of the Triassic.

The subfamily Anaptomorphinae contains the oldest and most generalized members of the tarsier-like primates and is the basal group of the extinct family Omomyidae. The best and most continuous record of anaptomorphine history is from rocks of early Eocene (Wasatchian) age in the Bighorn Basin of northwest Wyoming where eight genera and 14 species are recognized. Three of these species are new (Teilhardina crassidens, Tetonius matthewi, Absarokius metoecus), and four other new species are described from elsewhere (Tetonius mckennai, Absarokius gazini, A. australis, Strigorhysis huerfanensis). Teilhardina tenuicula and Absarokius nocerai are new combined forms. Absarokius noctivagus is considered to be a synonym of A. abbotti, and Mckennamorphus is a synonym of Pseudotetonius.

The evolution of dental characters in three principal morphologic clades of anaptomorphines from the Bighorn Basin is documented with the aid of numerous new specimens (75% of the sample is new) and with precise stratigraphic data. These major clades are Teilhardina–Anemorhysis, Tetonius–Pseudotetonius, and Absarokius. In each of these clades, evolution appears to have occurred gradually. In the first two clades it was mainly anagenetic, although each one included a minor branching event. In Absarokius, evolution was instead characterized by cladogenesis followed by continued (and continual) anagenetic change in each of the new lines. Anagenetic gradual evolution produced the new genus Pseudotetonius (from Tetonius) and possibly Anemorhysis (from Teilhardina). Similarly, the Absarokius metoecus lineage probably gave rise to late Wasatchian–early Bridgerian Strigorhysis. Evolution from Tetonius to Pseudotetonius has been clarified by establishment of five arbitrary stages of evolution (Tetonius–Pseudotetonius intermediates). Estimates of relative proportions of time represented by paleosols in different parts of the Willwood section suggest that cladogenetic speciation in Absarokius was almost certainly more rapid than anagenesis in Tetonius–Pseudotetonius.

Anagenetic character evolution and speciation in the anaptomorphine primates was typified first by increase, then decrease in variability, which resulted in measurable apomorphic morphologic change. Cumulation of changes of this sort created more extensive differences of importance at the species and genus levels. Introduction of changing character states and their tempo was staggered temporally, and new characters (and new taxa) are least separable from their antecedent states when they first appear. This evidence is in sharp contrast to predictions of the punctuated equilibria model of evolution. Because the emergence of diagnostic characters occurs gradually (in evolutionary terms) and not all at once (in temporal terms), and because diagnostic characters are the essence of the diagnosis (and thereby taxonomy), the implications of gradual evolution for both systematic paleontology and biostratigraphy are profound. Stasis exists in the evolution of individual characters over certain periods, but this study offers no evidence supporting either organismic stasis or even stasis in the dental evolution of the Anaptomorphinae over a period of about 4.8 million years.

An early Cambrian ichnofauna consisting of Helminthoidichnites tenuis, Helminthopsis tenuis, Multina isp., Oldhamia alata, and Pilichnus cf. dichotomus is documented from shallow-marine deposits ranging from the upper offshore to the offshore transition in the Puncoviscana Formation of northwest Argentina. Although the ichnogenus Oldhamia is more common in Cambrian deep-marine environments, this occurrence provides further evidence that it is also present in shallow-marine environments. The burrow network Multina (senior synonym of Olenichnus) is preserved at the base of tempestites, representing the activity of post-storm colonizers. A drowning surface separating offshore-transition deposits below from upper-offshore deposits above contains widespread evidence of trace fossils in direct association with matgrounds. The undermat miners Oldhamia alata and Pilichnus cf. P. dichotomus occur on this surface, revealing exploitation of organic matter in the biomat. Low sediment rate during drowning and paucity of bioturbation by sediment bulldozers may have promoted the establishment of the matground. In comparison with the simpler animal-matground interactions characteristic of the Ediacaran, the combination of Cambrian evolutionary innovations and the presence of microbial mats promoted more sophisticated interactions. Complex feeding trace fossils revealing that systematic undermat mining, as displayed by Oldamia alata and Pilichnus cf. dichotomus, is a product of the Cambrian explosion.

The Upper Missourian to lower Wolfcampian sequence (middle Kansas City through lower Council Grove Groups) of the Midcontinent U.S.A. (Kansas, Oklahoma, Nebraska, and Missouri) is divided into seven biostratigraphic zones defined chiefly upon first occurrences of Streptognathodus species. In ascending order, these are the: 1) Streptognathodus gracilis Zone; 2) Streptognathodus firmus Zone; 3) Streptognathodus pawhuskaensis deflectus Zone; 4) Streptognathodus virgilicus Zone; 5) Streptognathodus brownvillensis Zone; 6) Streptognathodus wabaunsensis s.l. Zone; and 7) Streptognathodus aff. barskovi Zone. The diagnostic Permian genus Sweetognathus first appears in the lower part of the S. aff. S. barskovi Zone. These zones coincide generally with Upper Carboniferous–Lower Permian conodont zones of Russia. Streptognathodus virgilicus, a new species common in the upper Shawnee and Wabaunsee Groups, is described.

The newly organized Long Island Natural History Museum (LINHM) has assembled a small collection of fossil vertebrates from the Cretaceous of Morocco. Among the remains in this collection are two spinosaurid (Theropoda) teeth and one sauropod tooth that we refer to either the Diplodocidae or Titanosauridae. Because of the scarcity of spinosaurid and Cretaceous sauropod teeth, a short description of the material is presented here. In addition to the dinosaurian remains, the collection includes an unidentified crocodilian tooth and a tooth identified tentatively as that of a pterosaur, which we also describe briefly. Furthermore, there are other fossil reptile teeth from the Ksar es Souk Province in the collections of the LINHM. Some of these may represent groups of reptiles other than those discussed here, but the taxonomic identity of these teeth is still being determined.

“Ladatheca” cylindrica (Grabau, 1900) was a eurytopic metazoan with a calcareous operculum and an elongate, gently tapering conch up to 15+ cm long and with an apical angle of approximately 0.75–2.0°. This apparent polychaete was geographically widespread in the sub-trilobitic Lower Cambrian of middle latitude, siliciclastic (middle and upper Placentian Series, Avalon Zone) and low latitude, carbonate platform (Tommotian Stage, Siberia(?) and Kazakhstan; and, probably, the upper Meishucunian Stage, southwestern China) sequences.

In situ conchs (vertically to steeply inclined, apex down) of “Ladatheca” cylindrica are common in deep subtidal, siliciclastic mudstones (Chapel Island Formation) and in a peritidal algal mud mound(?) limestone (West Centre Cove Formation) in southeastern Newfoundland. Closely juxtaposed conchs locally form a worm reef at the top of the West Centre Cove Formation. This structure is older than the oldest archaeocyathan build-ups and is the earliest known metazoan-constructed biostrome. “Ladatheca” cylindrica was a dominant element of the sessile benthos prior to its apparent ecological displacement by Coleoloides typicalis Walcott, 1889, in the upper Placentian Series.

Palynological analysis of the highly fossiliferous marine clays of the St. Erth Beds of Cornwall has revealed the presence of dinoflagellates, acritarchs and prasinophytes, scolecodonts, microforaminiferal linings, freshwater? invertebrates, freshwater algal spores, embryophyte spores and pollen, fungal spores, and plant cuticles. These groups are documented here and several, including the dinoflagellates, are reported from the St. Erth Beds for the first time.

The marine clays were deposited in warm, shallow waters of an inlet or embayment during a probable high stand in sea level. They are generally held to be of late Pliocene age, planktonic foraminiferal evidence placing them at between 1.9 and 2.1 Ma (late late Pliocene). Dinoflagellates are consistent with a late Pliocene age. Spores and pollen, if not reworked, suggest placement no higher than the lower part of the Tiglian Stage (upper Pliocene) of The Netherlands.

Analysis of all palynological groups permits terrestrial and marine climates to be evaluated independently. The spore-pollen assemblage has some thermophilic elements but mainly reflects a cool-temperate terrestrial climate. In contrast, dinoflagellates—dominated by gymnodinialean? and protoperidinioid cysts—indicate warm inner neritic waters and present some evidence for subtropical to tropical conditions with winter sea-surface temperatures above 15°. Increased influence of the Gulf Stream during the late Pliocene, perhaps superimposed upon a phase of global warming, is hypothesized to explain these differentially elevated marine temperatures.

The St. Erth inlet was not markedly brackish or hypersaline judging from the dinoflagellates, but rare freshwater algal spores attest either to some freshwater input or redeposition from sandy soils during marine incursion. High abundance of scolecodonts, about 1,500 to 2,000 per gram dry weight of sediment, allows speculation that the inlet hosted a thriving association of latest Pliocene marine annelid worms.

A species of algae incertae sedis, Halodinium scopaeum, and three species of dinoflagellate, Algidasphaeridium? euaxum, Sumatradinium pliocenicum, and Trinovantedinium sterthense, are proposed as new. The dinoflagellate genus Selenopemphix Benedek, 1972, is emended herein. Quinquecuspis Harland, 1977, is now validated by the transfer of Trinovantedinium concretum Reid, 1978, to Quinquecuspis Harland, 1977, as Q. concreta n. comb.

Watsonella crosbyi Grabau, 1900, a senior synonym of Heraultipegma varensalense (Cobbold, 1935) and H. yannense He and Yang, 1982, is the oldest known rostroconch. The species ranges through most of the Early Cambrian and has been recovered from temperate siliciclastic (Avalon Platform) and tropical carbonate (south China, Mongolia?, southern France) environments. Watsonella crosbyi occurs through approximately 880 meters of the sub-trilobitic Lower Cambrian of southeastern Newfoundland. Its lowest occurrence corresponds to the first appearance of relatively diverse small shelly faunas of the pre-Tommotian Watsonella crosbyi Zone (new).

The general form of Watsonella crosbyi conchs (laterally compressed, prosogyrate, elongate posterior, subdued comarginal growth lines, very thin shell with anterior and posterior gapes) is similar to that in a number of larger burrowing pelecypods, but this does not rule out other benthic habits. However, recovery of locally common in situ conchs (plane of commissure vertical, long axis subhorizontal) in the lower and upper parts of its stratigraphic range in southeastern Newfoundland corroborates an infaunal life habit for the species. The animal is a prominent element in faunas from offshore, cohesive, siliciclastic mudstones but also occurs in calcareous nodule-rich mudstones, shell hash limestones, and, infrequently, in peritidal algalaminate limestones. A phylogenetic sequence from laterally compressed monoplacophorans to early ribeiroid rostroconchs and leading to the oldest pelecypods was completed by the middle Early Cambrian and involved infaunal mollusks.

Samples from the Dumugol Formation were collected from eight measured sections and two cores in the so-called Baegunsan Syncline, located between eastern Yeongweol and Samcheog areas, Kangweon-Do, South Korea. A total of 7,813 identifiable conodonts were recovered from 146 samples. They are classified into 24 multielement species referable to 16 genera, and 37 form species belonging to 17 genera; six species are newly described: Distacodus dumugolensis, Parapanderodus acontiformis, Scolopodus longibasis, Scolopodus n. sp. A, Triangulodus dumugolensis, and Oistodus(?) sp. The Dumugol Formation is divided biostratigraphically into four conodont zones, viz, Chosonodina herfurthi-Rossodus manitouensis, Glyptoconus quadraplicatus, Paracordylodus gracilis, and Triangulodus dumugolensis zones in ascending order. These zones are correlated with those of the early Ordovician conodont faunas of North America, northern Europe, China, Australia, and Iran. The Dumugol Formation ranges from late Tremadocian to early Arenigian in age. The boundary between these two series lies between 70 and 100 m above the base of the Dumugol Formation in each of the sections.

The Sirius Passet biota of North Greenland is one of the oldest Cambrian lagerstätten, and although it is dominated by non-mineralized arthropods and lobopods, anomalocaridids have never been identified. Based on a single specimen, we herein describe for the first time an appendage with possible anomalocaridid affinities as suggested by an overall gross morphology similar to that of the frontal appendage of Anomalocaris from other localities. Tamisiocaris borealis n. gen. and n. sp. has an elongated appendage with paired spines along one margin, and differs from the frontal appendage of Anomalocaris in that segment boundaries are absent and ventral spines are relatively long and spineless. These differences may be taphonomic, but the entire surface of the appendage is covered in a fine fabric, making it unlikely that this appendage was originally segmented or sclerotized. the taxon is tentatively placed within Radiodonta, but this systematic placement cannot be confirmed while complete body specimens are lacking.

Plastomenidae is a poorly diagnosed clade of extinct soft-shelled turtles (Trionychidae) known from the Campanian to Eocene of North America. Five skulls, a mandible, two carapaces, and numerous plastral remains from the Hell Creek Formation (Late Cretaceous, Maastrichtian) of North Dakota and Montana are referable to Gilmoremys lancensis nov. comb., a taxon previously known from a carapace and xiphiplastron only. Gilmoremys lancensis is diagnosed by a carapace that is covered by elongate sinusoidal grooves, distally expanded second costals, hyoplastral shoulders, an extensive secondary palate with accessory ridges, an extremely elongate mandible, a contribution of the parietal to the wall of the orbit, and a posterior ossified narial canal. A phylogenetic analysis of all well-known plastomenid turtles establishes Gilmoremys lancensis as the most basal known plastomenid and reveals that cranial characters are more reliable in diagnosing plastomenid turtles, in particular the contribution of the parietal to the orbit wall and the extensive secondary palate. All plastomenid turtles with a locked entoplastron are placed in Hutchemys. Assuming that all taxa are monophyletic, the phylogenetic analysis implies that the G. lancensis lineage is the only one to go extinct at the K/T boundary, whereas the four remaining plastomenid lineages survive. Extensive ghost ranges are nevertheless apparent. Taphonomic considerations indicate that G. lancensis was a riverine turtle, whereas more derived plastomenids preferred swampy habitats.