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Isolated spines and scales from acanthodian fishes are common elements in vertebrate assemblages from the Early Devonian (Emsian) of Arizona, Idaho, Nevada, Utah, and Wyoming. The material described here is from the Sevy Dolomite and lower Grassy Flat Member, Water Canyon Formation, and includes one partially articulated specimen plus isolated fin spines and dermal plates of a new ?climatiid Sevyacanthus elliotti n. gen. and sp.; spines and shoulder girdle elements of a ?climatiid Nodocosta denisoni n. sp.; dentigerous jawbones from at least two ischnacanthiform taxa Ischnacanthus sp. and Cacheacanthus utahensis n. gen. and sp.; fin spines from a ?diplacanthiform Bryantonchus peracutus n. gen.; and scales of Ptychodictyon americanum n. sp. Most of the species appear endemic, although some show a close relationship with older Euramerican taxa (Ischnacanthus, Climatiidae sensu stricto) and younger Baltic taxa (Ptychodictyon rimosum, Nodocosta pauli).
The Tribes Hill Formation (upper Skullrockian) of New York records the earliest Ordovician diversification of cephalopods, in particular ellesmerocerids, on the east Laurentian, shallow carbonate platform. Revision of this cephalopod fauna on the basis of approximately 430 specimens collected across eastern New York has led to new information on inter- and intraspecific variation of the taxa and extensive synonymization of species-level taxa. The Ellesmeroceratidae and Protocycloceratidae, Ellesmeroceras, and Eremoceras are emended, Eorudolfoceras n. gen. and Dakeoceras champlainense n. sp. are erected. A rank abundance plot of the 342 specimens at a locality in the Lake Champlain lowlands provides information on the community structure of the nautiloid fauna, where small orthoconic taxa are shown to dominate strongly. The small orthocone Ectenolites was the most common genus in terms of total occurrences, was the most paleogeographically widespread genus, and was the only genus to cross the Cambrian-Ordovician boundary.
An abundant and diverse Late Griesbachian (Early Induan) Wordieoceras-dominated cephalopod fauna occurs in the lower part of the Daye Formation at the Wenjiangsi section, Guiding County, Guizhou Province, South China. The cephalopod fauna consists of 17 species belonging to 10 genera, including two nautiloid species and 15 ammonoid species representing the families Ophiceratidae, Proptychitidae, Meekoceratidae, and Khangsariidae. One genus and five species are new: Vishnuites wenjiangsiensis, Pseudovishnuites guidingensis, Wordieoceras guizhouensis, Gyrophiceras subplicatum, and Hubeitoceras? Wangi.
The postcranial skeleton of the Lower Permian temnospondyl Trimerorhachis insignis Cope, 1878 is described and figured in detail. Postcranial adaptations for an aquatic existence in T. insignis include the extensive ventral expansion of the interclavicle and clavicles and poorly ossified ends of the endochondral bones. The endochondral postcranial skeleton of T. insignis is paedomorphic through the process of neoteny, retaining an osteologically immature condition throughout morphogenesis. The endochondral postcranial elements display progressive morphological changes that do not stabilize in larger specimens, indicating indeterminate growth, with a correlation between size and degree of ossification. Some postcranial characteristics are present only in later morphogenetic stages of T. insignis.
Within the Temnospondyli, the postcranial skeleton of T. insignis is most similar to that of other members of the Dvinosauria. The morphology of the postcranial skeleton of T. insignis is consistent with a phylogenetic position more derived than the basal temnospondyls Balanerpeton woodi and Dendrerpeton acadianum, but less derived than the Euskelia plus Stereospondylomorpha. A sister-taxon relationship between the Dvinosauria and brachyopoids is not supported by postcranial characteristics of T. insignis.
Characteristics that develop last in morphogenesis in temnospondyls, and are consequently only present in well-ossified, morphogenetically mature temnospondyls, are absent in T. insignis due to paedomorphosis. Otherwise, the postcranial skeletons of T. insignis and other aquatic temnospondyls are similar to that of terrestrial temnospondyls, supporting the hypothesis that aquatic temnospondyls had terrestrial ancestors and are thus secondarily aquatic.
A review and revision of the Paleozoic proto-stomatopods results in the recognition of a new species of Tyrannophontes Schram, 1969, T. gigantion, from the Middle Pennsylvanian Mazon Creek, Essex biota. A new family, Daidalidae, and new genus, Daidal, are required to separate a previously recognized taxon, T. acanthocercus Jenner, Hof, and Schram, 1998. Both Perimecturus pattoni Peach, 1908 and Gorgonophontes cf. fraiponti (Schöllmann, 2004) appear at present to be best placed within Daidal, the latter as a new species, D. schoellmanni. The genus Gorgonophontes Schram, 1984 is allocated to a new family, Gorgonophontidae. Members of the family Tyrannophontidae reveal features of their maxillipeds that clearly relate them as a sister group to Unipeltata. A cladistic analysis of all known Paleozoic Palaeostomatopoda Brooks, 1962 and Archaeostomatopodea Schram, 1969 reveals a series of stem-group proto-mantis shrimp that lead to the crown-group Unipeltata Latreille, 1825.
This paper describes cranial and postcranial remains from Alligator olseni White, 1942 and Alligator cf. mefferdi Mook, 1946. An earlier phylogenetic data set has been augmented with new data from these fossils. Although membership in the clade Alligator is generally in accord with previous analyses, neither strict consensus nor Adams consensus trees could resolve placement of all members. Several lines of evidence pertinent to Alligator biogeography are analyzed. Alligator may have dispersed from North America into Asia prior to 15 million years ago, but conclusive evidence is lacking.
New phylogenies of endemic Pectinidae of the Galápagos Islands allow their endemic status to be assessed relevant to the relict theory of insular endemism. Nodipecten magnificus and Leopecten isabelensis n. sp. are neoendemic species that evolved in the Pliocene from ancestors in the tropical eastern Pacific and more remote ancestors in the Tertiary Caribbean Province before closure of transisthmian seaways. Spathochlamys vestalis, an eastern Pacific species whose incipiently neoendemic Galápagos representatives have diverged only slightly from the mainland stock, is related to an extant, broadly distributed western Atlantic sister species, S. benedicti, which has an ancestry traceable back to the Miocene in the Tertiary Caribbean Province. Euvola galapagensis is a paleoendemic whose ancestral lineage is extinct on mainland coasts. Veprichlamys incantata is a paleoendemic with an exclusively Pacific history, with its probable immediate ancestor occurring in the Pliocene of Ecuador and its more remote Miocene ancestors in the cooler waters of the southeastern Pacific. The high frequency of endemism and the evidence that originations are Pliocene or later are consistent with the high rates of morphological evolution attained by the Pectinidae relative to many other bivalves.
New species described are L. isabelensis of the Galápagos Islands and L. cocosensis of Cocos Island. Leopecten is shown to be restricted to the Americas and to differ morphologically from Flabellipecten, an extinct Neogene European genus that is phylogenetically not closely related. Based on a new phylogeny, the genus Lyropecten is extinct, and living representatives of the Lyropecten-Nodipecten clade are all in the genus Nodipecten.
The small crinoidal patch reef in the Bird Spring Formation near the mouth of Battleship Wash, Clark County, Nevada, has yielded the largest Early Permian crinoid fauna known in North America. Earlier studies of the fauna were based on 535 specimens. Additional collecting has yielded another 239 specimens. These new specimens provide new information about some of the earlier described species and include three new genera and seven new species, bringing the total recognized in the Battleship Wash fauna to 37 genera and 62 species. Representatives of the camerates, disparids, primitive cladids (cyathocrinitids and dendrocrinids), advanced cladids (formerly poteriocriniids), flexibles, and articulates are recognized in the Battleship Wash fauna.
Of particular significance among these new specimens is the presence of an actinocrinid. A specimen formerly identified from the fauna is here recognized as an articulate. This is the first report of an actinocrinid and an articulate from the Permian of North America. Based on the abundance of large specimens of cladids with 10 or more arms, the Battleship Wash fauna is interpreted to have lived in a nearshore high energy shelf environment, which agrees with the paleogeographic position previously recognized for the Bird Spring Formation.
New taxa introduced are: Poteriocrinites permicus n. sp., Bridgerocrinidae n. fam., Ekteinocrinus battleshipensis n. gen. and sp., Arroyocrius brachiatus n. sp., Plummericrinus jelli n. sp., Plummericrinus? bulbosus n. sp., Aesiocrinidae n. fam., Elassocrinus cyathus n. gen. and sp., Oklahomacrinus triangulus n. sp., and Pentaxocrinus quinarius n. gen. and comb.
Bomburia and Ellipsodon are poorly known taxa from the early Paleocene of western North America. New fossil material from New Mexico expands morphological information and allows taxonomic revision of these taxa. Bomburia is a valid genus, whereas Platymastus palantir, previously considered to be a loxolophine arctocyonid, is probably a junior synonym of B. prisca and as such reveals the upper molar morphology of this taxon.
Ellipsodon is highly derived relative to other mioclaenid condylarths. It has a reduced mesial dentition, with the probable loss of the P1/p1. P2–3/p2–3 are reduced and show a simple incisor-like morphology. M1/m1 and especially M2/m2 are simple with highly inflated protocones/protoconid-metaconids accentuating a mortar-and-pestle-like chewing function. The M3/m3 are more reduced than in any other mioclaenid.
Mioclaenidae is monophyletic and endemic to western North America. There is no support for a close relationship between Mioclaenidae and South American or African ungulates.
This paper describes nine brachiopod species (including two uncertain species) in eight genera of the Orthotetidina from the uppermost Changhsingian (latest Permian) of South China. They are the youngest silicified Permian brachiopods known in the world and the last representatives of the Orthotetida, a major brachiopod group that disappeared during the end-Permian mass extinction. Other than two uncertain species, all taxa are new, including Meekella dongluoensis, Perigeyerella guangxiensis, Ombonia capilla, Derbyia nigpi, Schuchertella fushuiensis, Streptorhynchus ovata, and Tropidelasma elongata.
The Kanosh Formation of the Great Basin of western North America contains the oldest abundant and moderately diverse bryozoan fauna known from North America. Six species are here described from this formation at Ibex in the Confusion Range, Utah. They comprise three species of esthonioporine stenolaemates and three trepostomes. Two new genera (Ibexella and Kanoshopora) and three new species (I. multidiaphragmata, K. droserae, and Eridotrypa hindsi) are introduced. The endozone of Kanoshopora n. gen. is very unusual among bryozoans in being filled with vesicles that are divided by beaded walls into longitudinal files close to the boundary with the exozone.
A bivalve fauna from the Permian—Triassic interval of the Dongpan section, Guangxi, South China is described herein. This bivalve fauna includes 16 species belonging to 10 genera. New taxa are Euchondria fusuiensis, Palaeoneilo qinzhouensis, and Claraia liuqiaoensis. Bed 12 of the interval (Talung Formation) contains the typical late Late Permian ammonoids: Huananoceras sp., Laibinoceras cf. L. compressum Yang, and Qiangjiangoceras sp. Bed 13 (Luolou Formation) contains typical Early Triassic bivalves Claraia dieneri Nakazawa, C. cf. C. wangi (Patte), and C. griesbachi (Bittner), which coexist with the earliest Triassic ammonoid Ophiceras sp. The bivalve and ammonoid distributions at the Dongpan section indicate that bed 12 should be assigned to the Late Permian, and bed 13 should be assigned to the Early Triassic. From the early Changhsingian to the Induan, the byssal notches of Claraia species tend to become progressively narrower, and change from being ventrally extended to being horizontally extended. The species level diversity of Claraia also increases through this interval.
Fossil dinoflagellates, when asymmetrical, almost always have features such as antapical horns on the right side reduced relative to features on the left side. A new species here described, Wilsonidium pechoricum, is therefore unusual in having a reduced left antapical horn. W. pechoricum seems to have originated in the northern Tethys in the latest Paleocene. It subsequently spread northwards and became widely distributed in the Peri-Tethys and parts of the Arctic region during the short interval known as the Initial Eocene Thermal Maximum (IETM). The new species was probably favored by extraordinary paleoecological conditions (high sea-surface temperatures and probably also high nutrient levels) prevailing in neritic waters of the IETM; a time during which aberrant morphotypes were also recorded among other planktonic protists. The apparent absence of W. pechoricum from the North Atlantic region suggests that the Turgay Strait may have functioned as a waterway between the Arctic and Peri-Tethys during the IETM. W. pechoricum is the oldest species of the genus Wilsonidium and possibly descended from the genus Apectodinium. Its early appearance points to a Late Paleocene radiation of the Wetzelielloideae before the well-known Early Eocene radiation in the subfamily, and its morphology is in accordance with a monophyletic origin of the group.
The Onychodontiformes is a poorly known sarcopterygian fish group, with four genera currently described, predominantly from the Middle-Late Devonian. A new onychodont, Bukkanodus jesseni n. gen. and sp., from the Fairy Formation, Victoria, Australia, is of Early Devonian (mid-late Pragian) age, representing one of the oldest known occurrences of this group. Other Pragian onychodonts are represented by a single lower jaw from China, while older occurrences (Lochkovian) include a lower jaw also from China and isolated teeth from Nevada. The Australian material, though disarticulated, includes skull, jaw, and palatal and dental specimens. These specimens share characteristics with younger onychodont taxa, including a laterally compressed tooth whorl with main and accessory rows containing an equal number of teeth, an anteriorly arched shape of the premaxilla, a lateral rostral bone participating in the orbital margin, parietals separated in the midline by small bones, the insertion of the basisphenoid region of the braincase into a posterior area on the parasphenoid, and an ethmoidal sensory canal running along the dorsal margin of the premaxilla rather than through the bone. Bukkanodus jesseni differs from other onychodonts in the presence of a distinct vomer, coronoids with fang pairs, a restricted herringbone pattern of ribs on enamel ridges of teeth, and the presence of a cluster of large pores on certain skull and jaw bones. The course of the ethmoid sensory canal and this cluster of pores are plesiomorphic features for the Onychodontiformes, also occurring in primitive sarcopterygian taxa such as Youngolepis, Powichthys, and Kenichthys. The opening of this cluster on the internal surface of the premaxilla resembles the rostral organ of derived coelacanths.
Taxa belonging to the Ceratoikiscidae are described in detail from two measured sections of Member C of the Cape Phillips Formation exposed along Rookery Creek, Cornwallis Island, Arctic Canada. The sections encompass uppermost Sheinwoodian (top lower Wenlock) to the base of the Gorstian (base Ludlow) and are dated by graptolites assigned to the Cyrtograptus perneri–Monograptus opimus Zone (upper Sheinwoodian), the Cyrtograptus lundgreni Zone (lower Homerian), and the Colonograptus praedeubeli–Colonograptus deubeli Zone (upper Homerian). Radiolarians are found in great abundance throughout the lower Homerian, allowing for the establishment of the first appearance of the genus Helenifore Ormiston and Nazarov. Helenifore is emended to accommodate the Silurian species H. quadrispina n. sp. and H. speciosus (Furutani 1990). One new genus, Kappaforma, including the new species, K. insecta, is described, as is the new species H. quadrispina. Ceratoikiscum octapleura Renz and C. armiger Furutani are synonymized with C. lenoides Renz, and H. planus Umeda is synonymized with H. speciosus.
Canids invaded South American during the Pliocene (2.8–3.1 Ma BP) as part of the Great American Biotic Interchange, but their record on the continent is relatively poor until the Pleistocene. However, even the Pleistocene record of the group is patchy and biased, with few records for the northern part of South America. In this paper we describe a new assemblage of canids found at the Inciarte asphalt pits (Zulia, Venezuela). These remains are associated with a variety of extinct Pleistocene mammals dated between 25–27 Ka BP. Canids in this assemblage include Protocyon troglodytes (Lund 1838), Protocyon sp., Canis dirus Leidy, 1858, Urocyon cf. U. cinereoargenteus (Schreber, 1775), and an indeterminate canid. This is the first record of Urocyon Baird, 1758 from the Late Pleistocene in South America and constrains the timing of its dispersal to South America. The distributional record of Protocyon Giebel, 1855 and P. troglodytes is expanded 1,500 km north of previous records and constitutes the first record of these taxa in Venezuela. The presence of C. dirus at Inciarte constitutes the fourth locality for this species in South America.
Three of Kitchin's (1903) trigoniid species, Trigonia trapeziformis, T. spissicostata, and T. cardiniiformis, have been frequently examined taxonomically, but their phylogenetic relationships remain uncertain. Taxonomic designations have ranged from grouping them within a single subgenus to separating them into different subfamilies. Principal factors affecting the previous studies include: excessive weighing of certain features from a typological perspective; phylogenetic relationships established on the basis of plesiomorphic characters which are applicable even at the family level. Although they are endemic to Kutch, India, species' ancestries were rarely sought from the regional taxa, a situation exacerbated by inadequate stratigraphic information. This study reveals that all the three species are both geographically and stratigraphically distinct, and their distribution is linked to major regression events. Since the latest Jurassic, the Kutch Basin experienced shallowing. The unstable environment triggered a substantial diversification of new forms. The present species are close morphologically to some endemic species of different genera. Detailed morphologic, morphometric, and cladistic analyses reveal affinities between ‘Eselaevitrigonia’ trapeziformis and Indotrigonia smeei, as well as ‘E.’ spissicostata and Opisthotrigonia retrorsa. It is believed that E. cardiniiformis evolved from ‘E.’ spissicostata. In each case, speciation took place in a very shallow, high-energy, nearshore environment and proceeded through various heterochronic processes. The pattern is consistent with a punctuated model of evolution. Gondwana fragmentation and rise of eustatic sea level during the Aptian opened up the central Indian oceanic corridor, prompting the spread of ‘Eselaevitrigonia’ to the Austral Province.
Lower Caradoc rhynchonelliformean brachiopods have been recovered from the uppermost part of the Postolonnec Formation and the base of the Kermeur Formation (Upper Aurelucian-lowermost Burrelian) below and above a significant oolitic ironstone bed in the Veryarc'h section, Armorican Massif, France. A new species, Tenuiseptorthis loii n. sp. and four species, Howellites sp., Drabovia pentagonomya Havlíček, 1971, Tafilaltia destombesi Havlíček, 1970 and Triplesia cf. T. simplex Havlíček, 1971 are described. These brachiopod taxa confirm, at generic and specific level, the very close paleobiogeographic relationships existing within the North Gondwana Realm between the Armorican Massif, Spain, Portugal and North Africa during Late Ordovician time.