Osteology and relationships of the temnospondyl genus Sclerocephalus

The temnospondyl Sclerocephalus from the Permo‐Carboniferous of Germany is one of the most completely preserved and most abundant Palaeozoic tetrapods. Here, we review the complete osteology of the genus, based on a range of fully grown specimens housed in public collections. Among the four valid species, Sclerocephalus haeuseri and Sclerocephalus nobilis reached an adult size of well beyond 1 m in length, and had robust postcranial skeletons. In the skull, the exoccipital and sphenethmoid bones were ossified, completing the well‐known ossification sequence in S. haeuseri. Large adults had an elongate trunk and a laterally compressed tail, and some individuals also retained lateral line sulci: features that taken together suggest an aquatic life. The coracoid, pubis, carpals, tarsals, and the bony tail are fully ossified in the largest specimens. The genus Sclerocephalus forms a weakly supported clade nesting firmly at the base of the Stereospondylomorpha, and the close resemblance between Sclerocephalus, Onchiodon, and Eryops is found to be partially based on shared derived states, but is mostly based on symplesiomorphies. Cladistic analysis of 54 characters and 18 taxa finds more support for the Eryopoidea hypothesis (Eryopidae + Stereospondylomorpha) than for the Euskelia hypothesis (Eryopidae + Zatracheidae + Dissorophoidea). This indicates that the large temnospondyls of the Permian and Mesozoic probably formed a natural group, and that the terrestrial adaptations of Eryops and the dissorophoids probably evolved by convergence.     

The stratigraphically oldest eryopoid temnospondyl from the Permo-Carboniferous Saar-Nahe Basin, Germany

An isolated mandible of a large temnospondyl from Theisbergstegen, Rhineland-Palatinate, is described that is derived from the Late Carboniferous Remigiusberg Formation of the Saar-Nahe Basin, southwestern Germany. The mandible is well preserved and exposed in lingual view, showing typical characteristics of basal eryopoids (i.e., eryopids plus stereospondylomorphs) such as the small size of the postglenoid area formed by the surangular and articular and the rather small Meckelian fenestra that fails to contact the postsplenial. It can be distinguished from the mandibles of all other known eryopoids from the Saar-Nahe Basin by characters such as a distinctly higher surangular process, higher, more strongly curved marginal teeth and the presence of a symphyseal lamina with at least one large parasymphyseal tooth. The mandible resembles those of eryopids rather than stereospondylomorphs in the angle of jaw being located on the level of the anterior portion of the surangular process and the dorsal edge of the mandibular ramus being dorsally concave. The described mandible is unequivocally the earliest known eryopoid from the Saar-Nahe Basin and shows that also large temnospondyls invaded the lakes of the Saar-Nahe Basin already during the “Remigiusberg invasion” in the Late Carboniferous.     

Early larval ontogeny of the Permo-Carboniferous temnospondyl Sclerocephalus

The early larval development of the temnospondyl Sclerocephalus sp. is analyzed, based on 38 specimens from the Lower Rotliegend (Permo-Carboniferous boundary) of the Saar-Nahe Basin (south-west Germany). The study focuses on the smallest larval specimens, which exemplify changes in both proportions and ossification patterns. In comparison with dissorophoid larvae, the skull ossifies more fully and at a much faster rate; the smallest specimens already have completely formed circumorbital bones that are sutured throughout. Sculpturing undergoes two marked changes, first from uniformly pitted to pits of variable size and regional differentiation, and finally to the origin of ridges. The palate of small larvae differs from that of larger specimens in patterns of dentition, having more teeth including a denticle field on the cultriform process. The mandible of small larvae is described for the first time, being narrower than in adults and having three dentigerous coronoid elements. The smallest specimens have poorly ossified neural arches, lack vertebral centra, and have faintly ossified humeri, femora, and very poorly developed distal elements. The posterior ribs, metapodia, and phalanges appeared after the dermal elements of the pectoral girdle, whereas the scapulocoracoid and ischium are absent throughout the larval period. Early growth and differentiation of the limbs and the ilium illustrates the developmental patterning of the appendages, which proceeded from proximal to distal. Dermal squamation is uniform in small stages, consisting of round or oval osteoderms with pronounced growth rings; in large larvae, they start to differentiate in certain body regions.     

Findings from the Peutz-Jeghers Syndrome Registry of Uruguay

Background

Peutz-Jeghers syndrome (PJS) is characterized by intestinal polyposis, mucocutaneous pigmentation and an increased cancer risk, usually caused by mutations of the STK11 gene. This study collected epidemiological, clinical and genetic data from all Uruguayan PJS patients.

Methods

Clinical data were obtained from public and private medical centers and updated annually. Sequencing of the STK11 gene in one member of each family was performed.

Results and discussion

25 cases in 11 unrelated families were registered (15 males, 10 females). The average age of diagnosis and death was 18 and 41 years respectively. All patients had characteristic PJS pigmentation and gastrointestinal polyps. 72% required urgent surgery due to intestinal obstruction. 3 families had multiple cases of seizure disorder, representing 20% of cases. 28% developed cancer and two patients had more than one cancer. An STK11 mutation was found in 8 of the 9 families analyzed. A unique M136K missense mutation was noted in one family. Comparing annual live births and PJS birth records from 1970 to 2009 yielded an incidence of 1 in 155,000.

Conclusion

The Uruguayan Registry for Peutz-Jeghers patients showed a high chance of emergent surgery, epilepsy, cancer and shortened life expectancy. The M136K missense mutation is a newly reported STK 11 mutation.     

A new species, Herbertia crosae (Iridaceae), from Uruguay

Herbertia crosae (Iridaceae) is described from the stony grasslands of northwestern Uruguay. The new species resemblesHerbertia lahue but can be easily distinguished by the narrower leaves, slender habit, the smaller pale lilac flowers, the presence of yellow spots at the base of the tepals, the red, adpressed hairs along the filament column, the presence of filaments free at the apex, the channeled style arm, the recurved secondary divisions of the style arm, and the smaller fruits. A key to the species of the genus is provided in which five species are now recognized.     

A Collection of Ticks (Ixodidae) from Wild Birds in Uruguay

Thirty nine wild birds from seven families (Alcedinidae, Emberizidae, Furnariidae, Parulidae, Trochilidae, Turdidae and Tyrannidae) were caught from 4 to 7 of February, 2004 at Rincón da Vassoura (31°15′ S 56°03′ W) Department of Tacuarembó, Uruguay. Ninety one nymphs and forty one larvae of Ixodidae were recovered from them. The majority of ticks were conventionally identified but 16S mitochondrial rDNA sequences were obtained for larvae and nymphs of Amblyomma with uncertain specific status to be compared with sequences of species from this genus. The 16S rDNA of Haemaphysalis juxtakochi Cooley was also obtained. Most ticks, 1 nymph of Amblyomma longirostre (Koch), 5 larvae of Amblyomma aureolatum (Pallas) and 3 nymphs of Amblyomma spp., 10 nymphs and 71 larvae of H. juxtakochi, 23 nymphs and 12 larvae of Ixodes pararicinus Keirans and Clifford, were found on the 5 Turdus albicollis Vieillot and 6 Turdus rufiventris Vieillot (Turdidae) caught. One nymph of A. longirostre and 2 nymphs of I. pararicinus were collected from the only Syndactyla rufosuperciliata (Lafresnaye) (Furnariidae) captured; 1 larva of I. pararicinus was collected on one of two Basileuterus leucoblepharus (Vieillot) (Parulidae) trapped and 1 nymph of A. longirostre was found on one of nine Elaenia parvirostris Pelzeln (Tyrannidae) captured. All these findings constitute new host records with the exception of I. pararicinus on S. rufosuperciliata, and stress the importance of Turdus as hosts for I. pararicinus, H. juxtakochi and A. aureolatum. Nymphs of H. juxtakochi and Amblyomma spp. were also found on man and vegetation.     

Biogeography and Breeding in Gymnotiformes from Uruguay

This study was carried out in Uruguay (30–35°S), South America, with two complementary approaches. First, an extensive exploration of Uruguayan freshwaters allowed us to assess the distribution of the two major species of Gymnotiformes (out of 4) across sites. Gymnotus carapo was uniformly distributed in Uruguayan territory, whereas Brachyhypopomus pinnicaudatus was observed in the northern and eastern part of the country. There was a highly significant negative correlation between the relative abundance of Brachyhypopomus pinnicaudatus and pH and water conductivity. Moreover, these environmental factors are significant contributors to its spatial differences in relative abundance. Second, temperature, conductivity, photoperiod, and the structure of a Brachyhypopomus pinnicaudatus population were analyzed across seasons in a small lake over a two-year period. Water temperature and photoperiod exhibited important seasonal changes, whereas water conductivity remained low and relatively constant. The presence of sexually mature males, females, and the sudden increase of juveniles indicated the occurrence of the breeding season in November, December, and January, coinciding with high mean water temperatures and extreme photoperiod. These results agree with previous data that support the hypothesis of temperature as an important environmental factor for the onset of breeding in Gymnotiformes from the temperate zone.     

A new earthworm trace fossil from paleosols: Aestivation chambers from the Late Pleistocene Sopas Formation of Uruguay

A new ichnotaxon, attributed to earthworm aestivation chambers, is described from paleosols of the Sopas Formation (Upper Pleistocene) of northern Uruguay. This ichnofossil consists of a spherical chamber with a constructed wall of imbricated faecal pellets and a filling of rounded to meniscate pellets arranged in winding strings. The strings may also be connected to specimens of Taenidium serpentinum in the paleosol, resulting in a compound trace fossil. Castrichnus incolumis igen. et isp. nov. is interpreted as an earthworm aestivation chamber based on its morphological similarity to the chambers produced by extant earthworms. As such, C. incolumis is considered an indicator of subaerial exposure, and also of seasonal climate. C. incolumis is the second trace fossil that can be attributed with certainty to earthworms. In addition, the Castrichnus–T. serpentinum compound specimens indicate that in paleosols, earthworms can be the producers of T. serpentinum. Aestivation chambers would represent a new ethological category.     

A potential vector of Schistosoma mansoni in Uruguay

Susceptibility experiments were carried out with a Biomphalaria straminea-like planorbid snail (Biomphalaria aff. straminea, species inquirenda) from Espinillar, near Salto (Uruguay), in the area of the Salto Grande reservoir, exposed individually to 5 miracidia of Schistosoma mansoni (SJ2 and BH2 strains). Of 130 snails exposed to the SJ2 strain, originally infective to Biomphalaria tenagophila, 30 became infected (23%). The prepatent (precercarial) period ranged from 35 to 65 days. The cercarial output was irregular, following no definite pattern, varying from 138 to 76,075 per snail (daily average 4.3 to 447.5) and ending up with death. Three specimens that died, without having shed cercariae, on days 69 (2) and 80 after exposure to miracidia, had developing secondary sporocysts in their tissues, justifying the prospect of a longer precercarial period in these cases. In a control group of 120 B. tenagophila, exposed to the SJ2 strain, 40 became infected, showing an infection rate (33.3%) not significantly different from that of the Espinillar snail (chi 2 = 3.26). No cercariae were produced by any of the Espinillar snails exposed to miracidia of the BH2 strain, originally infective to Biomphalaria glabrata. Four specimens showed each a primary sporocyst in one tentacle, which disappeared between 15 and 25 days post-exposure, and two others died with immature, very slender sporocysts in their tissues on days 36 and 54. In a control group of 100 B. glabrata exposed to BH2 miracidia, 94 shed cercariae (94%) and 6 remained negative. Calculation of Frandsen's (1979a, b) TCP/100 index shows that "Espinillar Biomphalaria-SJ2 S. mansoni" is a vector-parasite "compatible" combination.(ABSTRACT TRUNCATED AT 250 WORDS)     

Novel haloarchaeal 16S rRNA gene sequences from Alpine Permo-Triassic rock salt

Prokaryotic diversity in Alpine salt sediments was investigated by polymerase chain reaction (PCR) amplification of 16S rRNA genes, sequencing of cloned products, and comparisons with culturable strains. DNA was extracted from the residue following filtration of dissolved Permo-Triassic rock salt. Fifty-four haloarchaeal sequences were obtained, which could be grouped into at least five distinct clusters. Similarity values of three clusters to known 16S rRNA genes were less than 90%-95%, suggesting the presence of uncultured novel taxa; two clusters were 98% and 99% similar to isolates from Permo-Triassic or Miocene salt from England and Poland, and to Halobacterium salinarum, respectively. Some rock salt samples, including drilling cores, yielded no amplifiable DNA and no cells or only a few culturable cells. This result suggested a variable distribution of haloarchaea within different strata, probably consistent with the known geologic heterogeneity of Alpine salt deposits. We recently reported identical culturable Halococcus salifodinae strains in Permo-Triassic salt sediments from England, Germany, and Austria; together with the data presented here, those results suggest one plausible scenario to be an ancient continuous hypersaline ocean (Zechstein sea) populated by haloarchaea, whose descendants are found today in the salt sediments. The novelty of the sequences also suggested avoidance of haloarchaeal contaminants during our isolation of strains, preparation of DNA, and PCR reactions.     

Brachiopods and other fossils from the Permo-Triassic boundary beds of the Antalya Nappes (SW Taurus, Turkey)

An uppermost Permian-Lower Triassic biota of brachiopods, conodonts, algae and foraminifers from the Pamucak and Kokarkuyu formations at Çürük Da? (Antalya, Turkey) is here described. The brachiopods belong to two different assemblages: a lower assemblage, early Wuchiapingian in age, with Spinomarginifera cf. S. helica, Spinomarginifera cf. S. iranica, Alatorthotetina sp. ind., Orthothetina sp. ind., Ombonia antalyensis nov. sp. and few specimens of Pennospiriferinoidea; an upper assemblage, Changhsingian in age, comprising S. cf. S. iranica, Spinomarginifera cf. S. spinosocostata, Spinomarginifera sp. ind. and Orthothetina sp. ind., characteristic taxa of the low diversity survival brachiopod faunas of latest Permian age (Survival Fauna 1). The occurrence of the conodont Hindeodus cf. praeparvus above the brachiopod fauna confirms its Changhsingian age. The oolitic grainstones at the top of the Pamucak Formation contain Permocalculus sp., Macroporella cf. apachena, species of Hemigordius and Palaeozoic Lagenida. Coarse calcite fibrous cements pervade the oo-bioclastic grainstones, suggesting early marine cementation. The base of the Kokarkuyu Formation is characterized by the disaster forms Earlandia amplimuralis and “Cornuspira” mahajeri, gastropods and ostracods. The conodont Isarcicella lobata has been recovered 31 m above the base of the Kokarkuyu Formation, indicating the occurrence of the second Triassic conodont zone above the parvus biozone and below the staeschei biozone. The faunal content at the transition of the Pamucak and Kokarkuyu formations records the biotic survival in the aftermath of the end-Permian extinction. Facies evolution from lower energy inner platform wackestones and packstones to higher energy open platform oolitic grainstones indicates a transgression at the top of the Pamucak Formation, which continues into the Lower Triassic Kokarkuyu Formation.     

Morphometric study of allometric skull growth in the temnospondyl Archegosaurus decheni from the Permian/Carboniferous of Germany

The skulls of ninety-six specimens of the temnospondyl Archegosaurus decheni from the Permian/Carboniferous of Germany, ranging in length from almost 20 to almost 280 mm, are used in a morphometric analysis of cranial ontogeny. A Cartesian transformation, a bivariate regression analysis, and a principal component analysis (PCA) reveal changes of general skull proportions and of particular skull roofing bones during growth. The preorbital part of the skull exhibits a much faster growth rate than the postorbital region, whereas the orbits exhibit a considerable decrease in relative size. The skull bones possess low allometry coefficients of growth in width, what leads to a proportionally much more slender skull than in most other temnospondyls, comparable only to other archegosaurids, the cochleosaurid Chenoprosopus, and longirostrine stereospondyls like Australerpeton and trematosaurids. Distinctly negative allometry of the width of the cheek region, where part of the adductor musculature originated, suggests a weaker bite in A. decheni than in temnospondyls with broad-parabolic skulls like Onchiodon and Sclerocephalus. Results from the analysis of skull growth in A. decheni offer a biological interpretation of the life habits of this animal as becoming increasingly more adaptated to piscivory during ontogeny. The continuous growth of the skull with a gradual shift in proportions supports, in conjunction with morphological data, the hypothesis that A. decheni did not undergo a metamorphosis.     

Evidence for Permo-Triassic colonization of the deep sea by isopods

The deep sea is one of the largest ecosystems on Earth and is home to a highly diverse fauna, with polychaetes, molluscs and peracarid crustaceans as dominant groups. A number of studies have proposed that this fauna did not survive the anoxic events that occurred during the Mesozoic Era. Accordingly, the modern fauna is thought to be relatively young, perhaps having colonized the deep sea after the Eocene/Oligocene boundary. To test this hypothesis, we performed phylogenetic analyses of nuclear ribosomal 18S and 28S and mitochondrial cytochrome oxidase I and 16S sequences from isopod crustaceans. Using a molecular clock calibrated with multiple isopod fossils, we estimated the timing of deep-sea colonization events by isopods. Our results show that some groups have an ancient origin in the deep sea, with the earliest estimated dates spanning 232–314 Myr ago. Therefore, anoxic events at the Permian–Triassic boundary and during the Mesozoic did not cause the extinction of all the deep-sea fauna; some species may have gone extinct while others survived and proliferated. The monophyly of the ‘munnopsid radiation’ within the isopods suggests that the ancestors of this group evolved in the deep sea and did not move to shallow-water refugia during anoxic events.     

Length–weight relationships of eight fish species from the lower section of the Uruguay River (Río Negro, Uruguay)

This study reports length–weight relationships for Apareiodon affinis , Leporinus obtusidens , Cynopotamus argenteus , Loricariichthys melanocheilus , Parapimelodus valenciennis , Iheringichthys labrosus , Rhinodoras dorbignyi and Pachyurus bonariensis . Specimens were collected between 2006 and 2007 from the lower section of the Uruguay River. The study represents the first reference on weight–length relationships for three species and also provides the new maximum size for three species.     

The bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian Bystrowiella

Witzmann, F. and Soler-Gijón, R. 2010. The bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian Bystrowiella . — Acta Zoologica (Stockholm) 91 : 96–114
Bone histology of osteoderms in the armoured temnospondyl Peltobatrachus , plagiosaurids ( Gerrothorax , Plagiosuchus ) and dissorophids ( Aspidosaurus , Cacops , Platyhystrix ), as well as in the chroniosuchian Bystrowiella , is studied. The massive osteoderms of Peltobatrachus and Gerrothorax consist of homogeneous parallel-fibred bone, whereas in dissorophids, a lightly built, trabecular middle region is mantled by a thin cortex that is composed of a plywood-type structure. In Bystrowiella and Plagiosuchus , the osteoderms consist to a large degree of interwoven primary fibres and have cell lacunae that bear stumpy canaliculi. The differences in the histological structure of dissorophids and plagiosaurids suggest an iterative evolution of osteoderms. Furthermore, histology in Plagiosuchus indicates a metaplastic development of the osteoderms, whereas the osteoderms of Gerrothorax represent periosteal ossifications as in dissorophids. This suggests a convergent origin of osteoderms also within plagiosaurids. The extensive armour in Gerrothorax probably constituted a calcium reservoir, indicated by cyclical resorption events preserved in the external cortex and interpreted as a physiological response to periodic changes in salinity of the aquatic environment. In contrast, the unique osteoderm structure of dissorophids provides maximum stability and minimum bone mass, and is coherent with the interpretation that the osteoderms served to strengthen the vertebral column during terrestrial locomotion.     

Laidleria uncovered: a redescription of Laidleria gracilis Kitching (1975), a temnospondyl from the Cynognathus Zone of South Africa

The holotype skull of Laidleria gracilis Kitching has been prepared from the dorsal surface, and the skull disarticulated from the vertebral column to expose the occiput. Unexpected features of the dorsal skull roof are the absence of an otic notch and tabular horn. The occiput has reduced paroccipital processes with extremely small or absent posttemporal fenestrae as a consequence of the lack of the tabular horns. Both stapes are in place with their distal ends anterior to an exceptionally deep occipital flange formed by ventral processes from the postparietals, tabulars, squamosals and quadratojugals. They thus abut the ventral surface of the skull roof rather than a tympanum. The vertebrae have well ossified, almost spool-shaped, intercentra associated with small, paired, pleurocentra. It is concluded that L. gracilis should be left in its own family, the Laidleriidae, which may prove the sister group to the Rhytidosteidae.