Multiple Tooth Rows Research Articles

Reassessment of ‘Captorhinikos’ chozaensis, an early Permian (Cisuralian: Kungurian) captorhinid reptile from Oklahoma and north-central Texas

Abstract‘Captorhinikos’ chozaensis Olson, 1954 is a captorhinid eureptile with multiple tooth rows from the lower Permian (Cisuralian: Kungurian) Clear Fork Group of north-central Texas and the Hennessey Formation of Oklahoma. It has five maxillary and four dentary tooth rows. We re-examined the available specimens referred to ‘Captorhinikos’ chozaensis to elucidate aspects of its skeletal structure and assess its phylogenetic relationships. Our parsimony analysis confirmed previous suggestions that this taxon is not referable to the same taxon as Captorhinikos valensis Olson, 1954 (type species of the genus) and ‘Captorhinikos’ parvus Olson, 1970 and thus is placed in its own new genus, Sumidadectes. It also recovered Sumidadectes chozaensis n. comb. as the earliest-diverging moradisaurine captorhinid.UUID: http://zoobank.org/0f89869a-1889-4d90-b721-a89ba5f40c4b

Strange new spiders: on Roddenberryus, a new and unusual caponiid genus (Araneae, Caponiidae)

The new nopine genus Roddenberryus gen. nov. is erected to include in total five species: three new species, R. kirk gen. et sp. nov. (male and female) from Costa Rica, R. spock gen. et sp. nov. (female) from Campeche, Mexico and R. mccoy gen. et sp. nov. (male) from Baja California Sur, Mexico, as well as two species previously misplaced in Caponina Simon, i.e., R. sargi (Pickard-Cambridge, 1899) gen. et comb. nov. from Guatemala and R. pelegrina (Bryant, 1940) gen. et comb. nov. from Cuba. A male specimen reported as C. sargi Pickard-Cambridge from Costa Rica by E. Kritscher (1957) is assigned to Roddenberryus kirk together with one female collected at the same locality. The new genus is characterized by the distally projected endites and a triangular, projected labium, a conformation unique among nopines; also by a triangular, very short, scaly gladius, serrula with interspersed multiple tooth rows, and a tarsal organ with strongly projected margins. Roddenberryus shares with Tarsonops Chamberlin the cracked tarsi and metatarsi, with multiple adesmatic joints intertwined on the cuticle and an unusual internal respiratory system with both posterior tracheae fused in a single trunk.

Multiple Tooth-Rowed Parareptile From the Early Permian of Oklahoma

The Dolese Limestone Quarry near Richards Spur, Oklahoma includes an elaborate system of caves which have been infilled with early Permian fossil rich sediments. In operation for more than a century, the quarry yielded vast numbers of disarticulated skeletal elements of the most diverse assemblage of fully terrestrial tetrapods from the Paleozoic. Excavations carried out in this century are distinct in producing large numbers of articulated and semiarticulated skeletons, including numerous new taxa. Dolese is therefore unique among early Permian localities in being home to a diverse assemblage of small parareptiles, including two species ofDelorhynchus. Here we describe a new species of acleistorhinid, characterized by the presence of multiple tooth rows on the dentary, that can be identified with confidence as a third new species ofDelorhynchus. The multiple tooth rowed condition is deemed not to be a pathological condition, and appears to have formed in the same manner as in the captorhinid eureptileCaptorhinus agutithrough uneven growth of the tooth-bearing element.

Histology and \u03bcCT reveal the unique evolution and development of multiple tooth rows in the synapsid Endothiodon

Several amniote lineages independently evolved multiple rows of marginal teeth in response to the challenge of processing high fiber plant matter. Multiple tooth rows develop via alterations to tooth replacement in captorhinid reptiles and ornithischian dinosaurs, but the specific changes that produce this morphology differ, reflecting differences in their modes of tooth attachment. To further understand the mechanisms by which multiple tooth rows can develop, we examined this feature in Endothiodon bathystoma, a member of the only synapsid clade (Anomodontia) to evolve a multi-rowed marginal dentition. We histologically sampled Endothiodon mandibles with and without multiple tooth rows as well as single-rowed maxillae. We also segmented functional and replacement teeth in µ-CT scanned mandibles and maxillae of Endothiodon and several other anomodonts with ‘postcanine’ teeth to characterize tooth replacement in the clade. All anomodonts in our sample displayed a space around the tooth roots for a soft tissue attachment between tooth and jaw in life. Trails of alveolar bone indicate varying degrees of labial migration of teeth through ontogeny, often altering the spatial relationships of functional and replacement teeth in the upper and lower jaws. We present a model of multiple tooth row development in E. bathystoma in which labial migration of functional teeth was extensive enough to prevent resorption and replacement by newer generations of teeth. This model represents another mechanism by which multiple tooth rows evolved in amniotes. The multiple tooth rows of E. bathystoma may have provided more extensive contact between the teeth and a triturating surface on the palatine during chewing.

Unique Tooth Morphology and Prismatic Enamel in Late Cretaceous Sphenodontians from Argentina.

Mammals and reptiles have evolved divergent adaptations for processing abrasive foods. Mammals have occluding, diphyodont dentitions with taller teeth (hypsodonty), more complex occlusal surfaces, continuous tooth eruption, and forms of prismatic enamel that prolong the functional life of each tooth [1, 2]. The evolution of prismatic enamel in particular was a key innovation that made individual teeth more resilient to abrasion in early mammals [2-4]. Incontrast, reptiles typically have thin, non-prismatic enamel, and shearing, polyphyodont dentitions with multi-cusped or serrated tooth crowns, multiple tooth rows, rapid tooth replacement rates, or batteries made of hundreds of teeth [5-9]. However, there are rare cases where reptiles have evolved alternative solutions to cope with abrasive diets. Here, we show that the combined effects of herbivory and an ancestral loss of tooth replacement in a lineage of extinct herbivorous sphenodontians, distant relatives of the modern tuatara (Sphenodon punctatus) [10], are associated with the evolution of wear-resistant and highly complex teeth. Priosphenodon avelasi, an extinct sphenodontian from the Cretaceous of Argentina, possesses a unique cone-in-cone dentition with overlapping generations of teeth forming a densely packed tooth file. Each tooth is anchored to its predecessor via a rearrangement of dental tissues that results in a novel enamel-to-bone tooth attachment. Furthermore, the compound occlusal surfaces, thickened enamel, and the first report of prismatic enamel in a sphenodontian are convergent strategies with those in some mammals, challenging the perceived simplicity of acrodont dentitions [11-15] and showcasing the reptilian capacity to produce complex and unusual dentitions.

Computed tomographic analysis of the cranium of the early Permian recumbirostran ‘microsaur’ Euryodus dalyae reveals new details of the braincase and mandible

AbstractRecumbirostran ‘microsaurs’ are a clade of Palaeozoic tetrapods that possess numerous morphological adaptations for fossorial ecologies. Re‐study of many ‘microsaurs’ using tomographic methods has provided substantial new data on poorly known anatomy that informs their debated phylogenetic position. Recent studies have identified suites of features among recumbirostrans that place the group within crown Amniota, contrary to hypothesized positions on the amniote stem or the lissamphibian stem. Herein we describe the cranial anatomy of the early Permian gymnarthrid Euryodus dalyae through tomographic analysis of the holotype from South Grandfield, Oklahoma and new specimens from karst deposits near Richards Spur. The braincase of E. dalyae is composed of well‐ossified pleurosphenoids, orbitosphenoids that brace against the skull roof, and unpaired median ossifications. The otic capsules are well‐ossified, and the occiput is unconsolidated. Analysis of the mandibles, typically obscured in articulated specimens, reveals a second tooth row on the dentary, a feature previously unknown in ‘microsaurs’ that is reminiscent of the condition of the co‐occurring captorhinid Captorhinus aguti. The Richards Spur specimens share many of these features, including the second tooth row, but the neurocranium of the scanned specimen (OMNH 53519) differs from that of the holotype of E. dalyae (e.g. absence of unpaired median ossifications), and these specimens are referred to Euryodus sp. These data add to the growing neurocranial dataset of ‘microsaurs’, which is essential for iterative reevaluation of early tetrapod phylogeny. This discovery of multiple tooth rows in ‘microsaurs’ provides further support for the hypothesized close relationships between ‘microsaurs’ and reptiles.

Novel and Bizarre Abnormalities of the Tooth Row in Side-Blotched Lizards (Uta) and Rock Lizards (Petrosaurus).

Multiple tooth rows along the dentary or maxilla are present in many bony and cartilaginous fishes but occur infrequently in amniotes. Although two partially overlapping rows of teeth or a few doubled tooth positions were both previously reported in extant and extinct lizards, multiple rows of teeth across the entire dental or maxillary shelf were not previously documented in any lizard taxon. Here, we report one specimen of the side-blotched lizard Uta stansburiana and two specimens of the rock lizard Petrosaurus mearnsi that have two or more marginal tooth rows that overlap for most of the dental shelf. We also describe several other phrynosomatid lizard specimens with one or two doubled tooth positions per marginal tooth-bearing skeletal element. We examined 520 total specimens of pleurodont iguanian lizards and verified that aberrant tooth row and tooth position morphologies were almost exclusively present in phrynosomatid lizards. We hypothesize that developmental irregularities in the number of odontogenic bands or in the function of zones of inhibition may have resulted in the observed tooth row abnormalities. The expression of multiple tooth rows or doubled tooth positions may be phylogenetically informative morphologies of phrynosomatid lizards. This bears further investigation from developmental, genetic, ecological, and phylogenetic perspectives. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:2014-2025, 2020. © 2019 American Association for Anatomy.

Morphology and postnatal ontogeny of the dentition of Chthonerpeton indistinctum (Gymnophiona: Typhlonectidae)

Abstract The gross morphology, histology and postnatal ontogeny of the dentition of the viviparous and direct-developing typhlonectid Chthonerpeton indistinctum were described and compared with other caecilian species. C. indistinctum exhibited the typical pedicellated condition present in lissamphibians, with a conical monocuspid crown. Our histological analysis demonstrated that the tissue joining crown and pedicel was formed by two bands (internal and external), whereas the external band circumvented the complete periphery of the tooth junction. Likely this condition was not described for another gymnophionan species. In viviparous and some oviparous caecilians, dentition changes radically during ontogeny. Thus, there is a foetal dentition arranged in multiple rows of teeth (i.e. tooth patch), which is replaced by single tooth rows in neonate or juvenile individuals. Details of dentition in the lower jaw of neonate specimens are firstly reported for C. indistinctum herein, adding another member of Typhlonectidae. In some slightly larger specimens the foetal tooth patch on the lower jaw coexisted with a lingual row of the adult-type teeth, indicating that replacement of foetal dentition in the lower jaw did not take place just after birth. The number of teeth, a character widely employed among caecilian species descriptions, varies during postnatal ontogeny. Hence, we concluded that at least for typhlonectid caecilians, tooth number should not be considered as a character with a strong taxonomic value without considering the intraspecific ontogenetic variation. An extensive survey exploring the relationship between body length and tooth count becomes necessary to test the usefulness of tooth counts in species diagnosis.

Three new species of the cutthroat eel genus Dysomma, with comments on the variation of D. taiwanense (Anguilliformes: Synaphobranchidae).

Three new species of eels of the genus Dysomma are described from the western North Pacific Ocean off Taiwan. Dysomma formosa sp. nov., described from 34 specimens, differs from the congeners in having single row of 11-14 large compound teeth followed by 3-10 smaller teeth on lower jaw, 17-33 lateral-line pores, and 128-133 total vertebrae. Dysomma brachygnathos sp. nov., described from two specimens, differs from the congeners in the lack of a pectoral fin, having an anterior position of anus (preanal length 17.8-ca. 18.6% SL), 23-32 lateral line pores, a short lower jaw, and 131+‒136 total vertebrae. Dysomma robinsorum sp. nov., described from four specimens, differs from the congeners in having an anterior position of anus; preanal length 15.5-16.9% SL, no intermaxillary teeth; multiple rows of teeth on upper jaw; four compound teeth on vomer; teeth on lower jaw multiserial, those on inner row slightly enlarged, and 122-124 total vertebrae. Components of the variation of Dysomma taiwanense originally described from Taiwan are provided based on an additional 52 recently identified specimens.

New tetrapodomorph vertebrates from the Yam-Tesovo locality (Amata Regional Stage, Middle–Upper Devonian) of Leningrad Region, northwestern Russia

ABSTRACTEach piece of data is valuable for unearthing the earliest history of tetrapod origin. Despite frequently incomplete preservation, each skeletal element provides important information on the morphology, phylogeny and faunistic diversity of early tetrapodomorphs. We describe here new and earlier collected material from the fossil vertebrate site Yam-Tesovo on the Oredezh River (Leningrad Region, northwestern Russia) in the deposits of the Yam-Tesovo Formation within the Amata Regional Stage (?lowermost Frasnian, Upper Devonian). Upon similarity of their dermal ornamentation, two mandibular fragments are suggested to belong to the new tetrapodomorph taxon Rubrognathuskuleshovi n. gen. et sp. This species demonstrates a general ‘elpistostegalian' morphological pattern with some early tetrapod characters. The new taxon is characterised by an almost closed intercoronoid fossa, a prearticular that is strongly convex in section and bearing small teeth along its dorsal margin, low vertical coronoid laminae and coronoid fangs that enter the coronoid tooth row. The mandibular canal runs partly in open groove or opens to the surface by a row of large pores. The dermal ornament consists of a network of small ridges forming tubercles in the nodes. The postfrontal assigned to Tetrapodomorpha shows a ‘tetrapod-like' pits-and-ridges sculpturing and a supraorbital ridge characteristic of early tetrapods as well as ‘elpistostegalians'. Its long posterolateral bone margin demonstrates a lateral projection similar to that in Tiktaalik and unknown in other ‘elpistostegalians' and early tetrapods. An unusually flattened vomer is doubtfully related to the tetrapodomorph genus Livoniana Ahlberg, Lukševičs & Mark-Kurik, 2000, based upon characteristic multiple tooth rows. Teeth in rows decrease labially and show no clearly enlarged fang pairs. New finds of the last two decades present the earliest records of some tetrapod characters in non-limbed tetrapodomorphs. This challenges previous hypotheses on the origin of tetrapods.

The 'Tully monster' is a vertebrate.

Problematic fossils, extinct taxa of enigmatic morphology that cannot be assigned to a known major group, were once a major issue in palaeontology. A long-favoured solution to the 'problem of the problematica', particularly the 'weird wonders' of the Cambrian Burgess Shale, was to consider them representatives of extinct phyla. A combination of new evidence and modern approaches to phylogenetic analysis has now resolved the affinities of most of these forms. Perhaps the most notable exception is Tullimonstrum gregarium, popularly known as the Tully monster, a large soft-bodied organism from the late Carboniferous Mazon Creek biota (approximately 309-307 million years ago) of Illinois, USA, which was designated the official state fossil of Illinois in 1989. Its phylogenetic position has remained uncertain and it has been compared with nemerteans, polychaetes, gastropods, conodonts, and the stem arthropod Opabinia. Here we review the morphology of Tullimonstrum based on an analysis of more than 1,200 specimens. We find that the anterior proboscis ends in a buccal apparatus containing teeth, the eyes project laterally on a long rigid bar, and the elongate segmented body bears a caudal fin with dorsal and ventral lobes. We describe new evidence for a notochord, cartilaginous arcualia, gill pouches, articulations within the proboscis, and multiple tooth rows adjacent to the mouth. This combination of characters, supported by phylogenetic analysis, identifies Tullimonstrum as a vertebrate, and places it on the stem lineage to lampreys (Petromyzontida). In addition to increasing the known morphological disparity of extinct lampreys, a chordate affinity for T. gregarium resolves the nature of a soft-bodied fossil which has been debated for more than 50 years.

Multiple tooth-rowed captorhinids from the Early Permian fissure fills of the Bally Mountain Locality of Oklahoma

Captorhinids were Paleozoic eureptiles that originated in the Late Pennsylvanian in Laurasia and dispersed across the major landmasses of Pangaea by the Late Permian. Their evolutionary success as omnivorous and herbivorous members of Permian terrestrial communities has been attributed to the evolution of multiple marginal tooth rows. Multiple tooth rows evolved at least twice within Captorhinidae: once in the omnivorous Captorhinus aguti and again in the diverse subfamily of herbivorous moradisaurines. The earliest known moradisaurines co-occured with C. aguti in Lower Permian strata of Texas; however C. aguti is also known from much older fissure fills in the famous Dolese Brothers quarry near Richards Spur, Oklahoma, suggesting that C. aguti preceded any other multiple-rowed captorhinid. Here we report on new material of multiple-rowed captorhinids from the Lower Permian fissure fills of the Bally Mountain locality in Oklahoma, only 35 miles from Richards Spur. Some of this material is referrable to Captorhinikos valensis, which was previously only known from younger strata in Texas, making this species the geologically and phylogenetically oldest moradisaurine. Furthermore, we determined that Ca. valensis co-existed with C. aguti at Bally Mountain and we explore the potential for niche partitioning in these early captorhinids. Lastly, we assess the potential temporal and environmental differences between Bally Mountain and Richards Spur, in order to explain the abundance of herbivorous moradisaurines at Bally Mountain and the complete lack of moradisaurines at the neighbouring Richards Spur locality.

Patterns of tooth development and replacement in captorhinid reptiles: a comparative approach for understanding the origin of multiple tooth rows

ABSTRACTCaptorhinids are inherently interesting Paleozoic reptiles because they include the first terrestrial vertebrates to have multiple tooth rows on the maxilla and dentary. This may have been a key innovation that allowed captorhinids to diversify and disperse throughout the Permian Period of Pangea. We provide the first comparison of tooth development in captorhinids to determine how multiple rows of marginal teeth evolved within this clade. By comparing thin sections of multiple-rowed Captorhinus aguti from the Lower Permian of Oklahoma with the contemporaneous, single-rowed Captorhinus magnus, we provide evidence for variation in jaw growth, which establishes the number of tooth rows. Comparisons with the basal captorhinid Concordia cunninghami from the Upper Carboniferous of Kansas demonstrate that early captorhinids retained the typical amniote condition of replacing teeth in a manner similar to modern iguanian lizards. By comparing tooth development in C. aguti with other single-rowed captorhinids, we also demonstrate that the shedding of old teeth and the development of new teeth are not linked developmental processes in captorhinids. Instead, the fates of older generations of teeth are entirely dependent on their proximity to the lingual surface of the dentary where the tooth-producing organ, the dental lamina, would have been present. These peculiar features of the dentitions of captorhinids make them model taxa for examining patterns of tooth development and replacement.

A new captorhinid reptile, Gansurhinus qingtoushanensis, gen. et sp. nov., from the Permian of China

Captorhinids, a clade of Paleozoic reptiles, are represented by a rich fossil record that extends from the Late Carboniferous into the Late Permian. Representatives of this clade dispersed from the equatorial regions of Laurasia into the temperate regions of Pangea during the Middle and Late Permian. This rich fossil record shows that there was an evolutionary trend from faunivorous to omnivorous and herbivorous feeding habits within this clade. The discovery of well-preserved captorhinid materials in the Middle Permian of China allows us to determine that the new taxon, Gansurhinus qingtoushanensis, gen. et sp. nov, is a member of Moradisaurinae, a clade of captorhinids with multiple tooth rows arranged in parallel. The presence of this moradisaurine in the Middle Permian of south central Asia leads us to suggest that paleogeographic changes during the Permian, with part of what is today China becoming a large peninsula of Pangea, allowed these early reptiles as well as other terrestrial vertebrates to extend their geographic ranges to this region of the Late Paleozoic supercontinent.

Tadpole types of Chinese megophryid frogs (Anura: Megophryidae) and implications for larval evolution

Abstract The larval body shapes and oral discs of 30 frog species from the family Megophryidae from China were examined. Using a phylogenetic framework derived from a Bayesian analysis of published mitochondrial cytochrome b and 16S rRNA gene sequences, we deduced a pattern of historical change among megophryid larval forms. These larvae were categorized into four types according to their body shapes and oral discs: (A) Leptobrachiini type, (B) Lalax type, (C) Brachytarsophrys type, and (D) Megophryini type, of which B and C are novel types. Type A is characterized by a typical oral disc with multiple rows of teeth, representing the tadpole type of the most recent common ancestor of the family Megophryidae. Type B has a typical oral disc with reduced tooth rows, an elongated labium, and integumentary glands. Type C has no labial teeth and a smaller umbelliform oral disc. Type D is characterized by a lack of labial teeth, an enlarged umbelliform oral disc, representing the tadpole of the most recent common ancestor of the subfamily Megophryinae. Our analysis supports the hypothesis that the umbelliform oral disc is apomorphic and also reveals the close association between morphology and microhabitat.

Reiszorhinus olsoni, a new single-tooth-rowed captorhinid reptile from the Lower Permian of Texas

ABSTRACT A new genus and species of captorhinid reptile from the Lower Permian Waggoner Ranch formation of north-central Texas, Reiszorhinus olsoni, is described on the basis of well-preserved cranial material. The holotypic specimen, consisting of a partial skull and mandible, was misidentified by S. W. Williston in 1917 as Labidosaurus hamatus. Autapomorphies of the new taxon include recurved teeth and the possession of an extremely large Meckelian foramen on the medial surface of the lower jaw. The new taxon retains the primitive condition of a single row of dentary and maxillary marginal teeth. It is distinguished from other single-tooth-rowed captorhinids, with the exception of Labidosaurus hamatus, by its large size, and it lacks the marked cheek expansion found in other large captorhinids. PAUP and Bayesian analyses suggest the new genus is the most basal of described captorhinid genera with the exceptions of Romeria, Concordia, and Protocaptorhinus. The description of a new, large, single-tooth-rowed form suggests that, in addition to multiple tooth rows, relatively larger size evolved more than once in the basal reptilian family Captorhinidae.

The morphology of prehatching embryos ofCaecilia orientalis(Amphibia: Gymnophiona: Caeciliidae)

The state of development of advanced embryos of the direct-developing Ecuadorian caecilian Caecilia orientalis (Caeciliidae: Gymnophiona: Amphibia) was examined. Because it is established that development is correlated with reproductive modes in a number of features, we included comparison with taxa that represent the major reproductive modes and all of the modern normal tables and ossification sequences. The embryos of C. orientalis most closely resemble those of stage 47/48 Gegeneophis ramaswamii, an Indian caeciliid, and stage 47/48 Hypogeophis rostratus, a Seychellian caeciliid, both direct developers, in details of bone mineralization, chondrocranial degeneration, and vertebrogenesis. They are most like stage 45 H. rostratus in external features (gills, pigmentation, etc.). They are less similar to prehatchings of Ichthyophis kohtaoensis, an ichthyophiid with free-living larvae, and to fetuses of the viviparous caeciliid Dermophis mexicanus and the viviparous typhlonectid Typhlonectes compressicauda at comparable total lengths in both skeletal development and external features. The similarity of developmental features among the direct-developers suggests a correlation with mode of life history. A noteworthy feature is that C. orientalis has an armature of multiple rows of teeth on the lower jaw with tooth crowns that resemble the "fetal" teeth of viviparous taxa and that are covered with a layer of oral mucosal epithelium until full development and eruption, but the upper jaw bears a single row of widely spaced, elongate, slightly recurved teeth that resemble those of the adult.

Evolutionary trend in feeding habits of Girella (Perciformes: Girellidae)

Although some Girella species are herbivorous, having basically tricuspid teeth, some are omnivorous. To determine the evolutionary trends in feeding habits of Girella, the phylogenetic relationships of several species of Girella were estimated by partially sequencing the mitochondrially encoded NADH dehydrogenase subunit 2 gene, and the dentition and adductor mandibulae complex of each species were examined. The cladogram determined from the mitochondrial DNA analysis indicated that multiple tooth-rows containing incisor-like teeth existed in adults of the ancestral species of Girella, species with a single tooth-row of tricuspid teeth in the adult stage having diverged subsequently on several occasions. The tendinous connections between each section of the adductor mandibulae complex are believed to have been simple in the ancestral species, more complicated connections also having diverged later on several occasions. Multiple tooth-rows containing incisor-like teeth and the simple adductor mandibulae complex are deduced as adaptations to herbivory; on the other hand, a single tooth-row of tricuspid teeth and the complicated adductor mandibulae complex are deduced as adaptations to omnivory. Therefore, the ancestral species of Girella is suggested as having been adapted to herbivory, with species adapted to omnivory having diverged on several subsequent occasions.

Cranial anatomy of Coloraderpeton brilli, postcranial anatomy of Oestocephalus amphiuminus, and reconsideration of Ophiderpetontidae (Tetrapoda: Lepospondyli: Aistopoda)

ABSTRACT The cranial anatomy of Coloraderpeton brilli Vaughn and postcranial anatomy of Oestocephalus amphiuminus Cope are reconsidered in light of new ophiderpetontid material from Nýřany, Czech Republic. Coloraderpeton is distinct from Oestocephalus amphiuminus in having a quadrate region extended farther posterior of the occiput and a tabular restricted from the lateral temporal margin by the supratemporal. In contrast to the original description, Coloraderpeton, like all lepospondyls, lacks an intertemporal. Coloraderpeton has widely spaced teeth, which bring into question the utility of this character for separating Ophiderpeton from Oestocephalus. Coloraderpeton has multiple rows of teeth on its palatoquadrate, as opposed to the single row in Oestocephalus. Oestocephalus has approximately 110 vertebrae. Vertebrae are not added posteriorly with growth, making vertebral counts of systematic significance in aïstopods. Transverse processes remain laterally directed throughout the column, unlike Phlegethontia, which has an anterior migration of the bases of the transverse processes, and an anterior inflection of the distal transverse processes that becomes more pronounced posteriorly. Ribs are present to about the 70th vertebra, leaving 40 rib-free caudal vertebrae, contrasting with the 100–160 rib-free caudal vertebrae of Phlegethontia. Ribs are “k-shaped,” with an anterior costal process and a long posterior process on either side of the tuberculum. No distinction can be made among any of the species from Linton, Ohio, Mazon Creek, Illinois, and Nýřany, Czech Republic, and so all are included within Oestocephalus amphiuminus. The exception is O. nanum from Newsham, Northumberland, which has reduced dorsal osteoderms. Preliminary phylogenetic analysis indicates that Ophiderpetontidae as previously understood are paraphyletic, and a new family, Oestocephalidae, is established to accommodate Oestocephalus and Coloraderpeton.

A proposal for a standard terminology of anatomical notation and orientation in fossil vertebrate dentitions

ABSTRACT There is little consistency in the notation and orientation terminology used in discussions of non-mammalian fossil venebrate dentitions. The standardization of this terminology, as done in the medical and dental sciences, would facilitate all future research on fossil teeth. For mammals, we recommend following convention, where incisors, canines, premolare, and molars are abbreviated as In, Cn, Pn, and Mn (n = tooth number) in upper jaws and as in, cn, pn, and mn in lower jaws. Right, left, and deciduous teeth are indicated by R, L, and D (e.g., DP4, Rp2). For non-mammals, which can have dentigerous premaxillae, maxillae, and dentaries, as well as additional tooth-bearing bones (e.g., vomers, palatines, pterygoids, ectopterygoids, sphenoids, splenials, and even parasphenoids), we encourage identifying teeth using the bone abbreviation (e.g., pmn, mxn, dn, vn, pain). A number and slash (/) combination can be used to distinguish between multiple tooth rows (e.g., Pal1/n, Pal2/n), and specimen-specific maps can be created for very complicated dentitions. We suggest the use of the terms mesial and distal to designate tooth surfaces and directions facing toward and away from the mandibular symphysis. Labial is offered for those surfaces and directions facing the lips or cheeks and lingual for those facing the tongue. We offer the terms basal for the direction toward crown bases, apical for the direction toward crown tips, occlusal for views of the occlusal surfaces, and basal and root apical for views of crown bases and roots, respectively.