Abstract: The non-dinosaurian dinosauriform silesaurids are the closest relatives of crown-group dinosaurs and are thus, important for understanding the origins of that group. Here, we describe the limb bone histology of the Late Triassic silesaurid Sacisaurus agudoensis from the Candelária Sequence of the Santa Maria Supersequence, Rio Grande do Sul state, Brazil. The sampled bones comprise eight femora and one fibula from different individuals. The microscopic analysis of all elements reveals uninterrupted fibrolamellar bone tissue indicating rapid growth. A transition to slower growing peripheral parallel-fibered bone tissue in some individuals indicates a decrease in growth rate, suggesting ontogenetic variation within the sample. The osteohistology of Sacisaurus agudoensis is similar to that of other silesaurids and supports previous hypotheses that rapid growth was attained early in the dinosauromorph lineage. However, silesaurids lack the complex vascular arrangements seen in saurischian dinosaurs. Instead, they exhibit predominantly longitudinally-oriented primary osteons with few or no anastomoses, similar to those of some small early ornithischian dinosaurs. This simpler vascular pattern is common to all silesaurids studied to date and indicates relatively slower growth rates compared to most Dinosauria.

A planície costeira do estado do Rio Grande do Sul, no sul do Brasil, inclui quatro sistemas deposicionais do tipo laguna-barreira formados por sucessivas transgressões marinhas do Quaternário, correlacionadas aos estágios isotópicos marinhos (MIS) 11, 9, 5 e 1, apesar da escassez de idades absolutas. Este estudo descreve um máximo transgressivo marinho mais antigo que o MIS 5, com base na estratigrafia, datações e fósseis encontrados na fácies marinho raso de uma barreira costeira (Barreira II). Esta fácies encontra-se exposta ao longo das barrancas do Arroio Chuí, é composto por areia quartzosa fina, bem-selecionada, com icnofósseis Ophiomorpha nodosae Rosselia sp., e conchas de moluscos. O registro sedimentar indica agradação da costa seguida por regressão do nível do mar e progradação da linha de costa. Datações por termoluminescencia (TL) e ressonância do spin do elétron (ESR) em sedimentos e conchas fósseis indicam uma idade de ∼220 ka para o final desta transgressão, correlacionando-a, portanto, ao MIS 7 (sub-estágio 7e). Dados altimétricos indicam amplitude máxima de aproximadamente 10 metros acima do nível atual do mar, mas processos tectônicos podem estar envolvidos. Condições paleoceanográficas à época da transgressão e correlações com outros depósitos da costa brasileira também são discutidos.

The coastal plain of the state of Rio Grande do Sul, in southern Brazil, includes four barrier-lagoon depositional systems formed by successive Quaternary sea-level highstands that were correlated to marine isotope stages (MIS) 11, 9, 5 and 1, despite the scarcity of absolute ages. This study describes a sea-level highstand older than MIS 5, based on the stratigraphy, ages and fossils of the shallow marine facies found in coastal barrier (Barrier II). This facies outcrops along the banks of Chuí Creek, it is composed of fine, well-sorted quartz sand and contains ichnofossils Ophiomorpha nodosa and Rosseliasp., and molluscan shells. The sedimentary record indicates coastal aggradation followed by sea-level fall and progradation of the coastline. Thermoluminescence (TL) and electron spin resonance (ESR) ages from sediments and fossil shells point to an age of ∼220 ka for the end of this marine transgression, thus correlating it to MIS 7 (substage 7e). Altimetric data point to a maximum amplitude of about 10 meters above present-day mean sea-level, but tectonic processes may be involved. Paleoceanographic conditions at the time of the highstand and correlations with other deposits in the Brazilian coasts are also discussed.

New material of Tapirus from the late Pleistocene of Rio Grande do Sul State is described, and other specimens previously collected are reviewed. The material comes from Alegrete (Sanga da Cruz Creek), Dom Pedrito (São Luiz cattle ranch), Iraí, Quaraí (Cerro da Tapera), and Santa Vitória do Palmar (Hermenegildo Beach). The specimens from Iraí are referred to the extant species, T. terrestris, on the basis of their size and morphology. Specimens from Sanga da Cruz Creek, Hermenegildo Beach, São Luiz cattle ranch and Cerro da Tapera are very fragmentary or present no diagnostic characters, and are tentatively assigned to Tapirus cf. T. terrestris. We confirm the presence of the T. terrestris in the upper Pleistocene of Rio Grande do Sul state. Currently, there are neither archaeological nor historical records of this species for the southern region of this state.

Nuevos materiales del género Tapirus de Pleistoceno tardío del Estado de Rio Grande do Sul son presentado, mientras otros especímenes previamente recolectados son revisados. El material descripto proviene de las municipalidades de Alegrete (Sanga da Cruz), Dom Pedrito (Estancia São Luiz), Iraí, Quaraí (Cerro da Tapera), y Santa Vitória do Palmar (Playa del Hermenegildo). Los especímenes de las localidades de Iraí fueron comparados con otras especies del género, y debido a su morfología y tamaño, ellos fueron referidos a la especie reciente, T. terrestris. Los especímenes de Sanga da Cruz, Playa del Hermenegildo, Estancia São Luiz y Cerro da Tapera están muy fragmentados o no presentan caracteres diagnósticos, y fueron tentativamente asignados a Tapirus cf. T. terrestris. Nosotros confirmamos la presencia de T. terrestris en el Pleistoceno tardío del Estado de Rio Grande do Sul. Actualmente, no hay registros arqueológicos ni históricos de esta especie para la región sur de este estado.

O gênero Cavia inclui quatro espécies no Brasil, C.aperea (pelo menos duas subespécies, C.a.aperea e C.a.pamparum), C.magna, C.intermedia e C.fulgida. Visando contribuir para o conhecimento da anatomia e para a distinção dessas espécies, descreve-se o sincrânio (crânio e mandíbula) de exemplares de C.a.pamparum do Rio Grande do Sul e compara-se com exemplares de C.magna deste estado e de Santa Catarina, C.intermedia da ilha de Moleques do Sul, na costa catarinense, e C.fulgida de Minas Gerais e Paraná. Cavia aperea possui crânio baixo e longo; rostro comprimido lateralmente; constrição interorbital marcada; órbita elíptica com ampla comunicação com a fossa temporal; forâmen infra-orbital amplo e deprimido; mandíbula longa e baixa, com processo angular não refletido lateralmente; fórmula dentária 1I.0C.1P.3M; dentes hipselodontes; molariformes formados por dois prismas, o anterior laminar e o posterior cordiforme. Cavia aperea distingue-se de C.magna pelo menor desenvolvimento da porção rostral do crânio e da raiz ventral do processo zigomático do maxilar; forâmen infraorbital mais deprimido; porção posterior dos frontais e parietais menos convexos; apófises paraoccipitais mais curtas e curvas anteriormente; incisivos superiores mais estreitos e geralmente opistodontes (proodontes em C.magna); fenda terciária externa (fte) mais profunda e com mais cemento; prolongamento anterior à fte mais desenvolvido e constrição na base do prolongamento posterior. Cavia intermedia possui jugal curto; fossa jugal reduzida/ausente; depressão na região interorbital bem marcada; crista sagital larga; constrição lateral no basisfenóide tênue; forâmen magno amplo; supra-occipital baixo; fte rasa e prolongamento anterior pouco desenvolvido; p4 com prisma posterior tão largo quanto o anterior; m3 com prisma anterior mais largo que o posterior e fenda secundária interna menos profunda. Cavia fulgida caracteriza-se por suas dimensões menores e fte muito profunda. Entretanto, exemplares do sul do Brasil com estes caracteres, mas coloração não típica de C.fulgida, podem pertencer à C.aperea, sendo necessários mais estudos para esclarecer esta questão.

The genus Cavia includes four species for Brazil, C.aperea (at least two subspecies, C.a.aperea and C.a.pamparum), C.magna, C.intermedia and C.fulgida. Aiming to contribute to the anatomy and to distinction of these species the syncranium (skull and mandible) of C.a.pamparum from Rio Grande do Sul State is described and compared with C.magna from Rio Grande do Sul and Santa Catarina States, C.intermedia from Moleques do Sul island on Santa Catarina's coast, and C.fulgida from Minas Gerais and Paraná States. Cavia aperea skull is lower and longer, with laterally compressed rostrum; marked interorbital constriction; elliptical orbit with broad communication with temporal fossa; broad and depressed infraorbital foramen; longer and lower mandible, with angular process not reflected laterally; dental formula 1I.0C.1P.3M; hypselodont teeth; molariforms formed for two prisms, the anterior laminar and the posterior cordiform. Cavia aperea distinguishes from C.magna by a less developed rostrum and ventral root of zygomatic process of maxilla; infraorbital foramen more depressed; posterior portion of dorsal surface of frontals and parietals less convex laterolaterally; paraoccipital apophysis shorter and more bent anteriorly; superior incisors narrower and generally opistodonts (proodonts in C.magna); external tertiary notch (fte) deeper with a thicker cement; anterior prolongation to fte more developed; and a constriction at the bottom of posterior prolongation. Cavia intermedia is distinguished by a shorter jugal; reduced/absent jugal fossa; more prominent depression in the interorbital region; larger sagittal crest; less marked lateral constriction in basisphenoid; wider magnum foramen; lower supraoccipital; fte less marked and its anterior prolongation little developed; the anterior prism of p4 as large as the posterior; anterior prism of m3 larger than posterior; shallow internal secondary notch in m3. Cavia fulgida differentiates by the smaller dimensions and a deeper fte. However southern Brazil specimens with these characters, but not typical coloration of C.fulgida, should belong to C.aperea. More studies are needed to clarify this issue.

Observou-se grande variabilidade anatômica no sincrânio de Otaria byronia (Blainville, 1820) e de Arctocephalus australis (Zimmerman, 1783), com correspondentes implicações na sistemática dos Otariidae. As principais diferenças observadas entre as duas espécies foram a largura do rostro, exposição (ou não) do etmóide na órbita, vacuidade palatino/pterigóide, extensão do maxilar, concavidade e forma do palato, tamanho/forma da órbita/processo supra-orbital, altura/forma do palato, tamanho/forma da órbita/processo supra-orbital, altura/forma do arco zigomático, forma do hâmulo pterigóide, tamanho de processos e cristas em geral, esfenóide e neurocrânio; presença ou não do canal vidiano e transverso; forma do pétreo e proporções do processo angular secundário. Enquanto algumas diferenças (etmóide) são bastante incomuns entre espécies contemporâneas pertencentes à mesma família, muitas outras são de natureza alométrica. Algumas diferenças são peramórficas: tamanho do crânio, do palato e das cristas (hipermórficos em O. byronia). Outros caracteres são pedomórficos em O. byronia: forame incisivo, processo maxilar do frontal e canais vidianos. As principais diferenças entre machos e fêmeas de O. byronia, e similiraridades entre os machos desta espécie e A. australis estão relacionadas a modificações no tempo/taxa de desenvolvimento. Alguns caracteres usualmente empregados na sistemática do grupo não foram corroborados, principalmente referentes à fossa naso-labialis, sutura jugo-temporal, meato acústico interno, entotimpânico e extensão do pétreo.

A high degree of anatomical variability in many structures of Otaria byronia (Blainville, 1820) and Arctocephalus australis (Zimmerman, 1783) was observed, which should yield serious implications to the systematics of Otariidae. The main differences observed between the two species were: the breadth of the rostrum, the exposure (or not) of the ethmoid in the orbit, the palatine/pterygoid vacuity, the extension of the maxilla, the concaveness and shape of the palate, the size/shape of the orbit/supra-orbital process, the height/shape of the zygomatic arch, the shape of the hamulus pterygoideus, the size of processes and crests, the proportions of the sphenoid and of neurocranium, the occurrence or not of the vidian and transverse canals, the relieves of the cranial fossae, and the size of secondary angular process. While some differences (ethmoid) are rather unusual between contemporary species belonging to the same family, many others are of allometric nature. Some differences are peramorfic: skull size, palate size and crests size (hypermorphic in O. byronia). Others caracters are pedomorphic in this species: incisive foramen, maxille process of the frontal and vidian channels. The main differences between males and females of O. byronia, and similitarities between de males of this species and A. australis are related to developmental modification in rate or in the timing too. Some characters usually used in the group's systematics were not corroborated, mostly those related to the naso-labialis fossa; zygomatic-temporal suture; internal acoustic meatus and entotimpanic.

Pesquisou-se o nível de desgaste dental (atrição e/ou abrasão) em 168 espécimes de Didelphis albiventris e D. marsupialis (gambás) do sul do Brasil. O desgaste foi muito importante, com elevada freqüência de dentina terciária e de exposição da câmara coronária e/ou do canal radicular, devido à associação de fraturas e desgaste, pois as fraturas predispõem ao desgaste e este favorece as fraturas. O grau de desgaste aumentou com a idade dos animais. A ordem crescente na freqüência de dentina terciária nos dentes caudais aos caninos foi: primeiro, segundo e terceiro molares, terceiro e segundo pré-molar, e quarto molar. Diferentemente de outros onívoros, em Didelphis o desgaste dentário parece mais relacionado às fraturas devidas aos alimentos (seguida de atrição/abrasão) do que ao contato entre os dentes. Ao contrário da literatura, os molares tribosfênicos não parecem "ideais" para tal dieta onívora, o que é evidenciado pela elevada freqüência de desgaste, fraturas e exposição da câmara coronária ou do canal radicular.

This work deals with the study of dental wear down (atrittion and/or abrasion) in 168 specimens of Didelphis albiventris and D. marsupialis from Southern Brazil. Wear down was very important, with high frequency of tertiary dentine and exposition of the pulp cavity/radicular canal, due to the association of fractures and wear down. Fractures predispose wear down which, on the other side, favors fractures. The degree of attrition increased with age. The order of growing frequency of tertiary dentin in poscanines was: first, second and third molars, third and second premolars, and finally fourth molar. Differently from others omnivorous in Didelphis tooth wear down seems rather related to fractures due to food (followed by attrition) than to teeth contact. Contrary to literature, tribosphenic molars seems not to be "ideals" for such omnivorous diet, as is evident from the high frequency of wear down, fractures and teeth cavities exposition.

Bone diseases and tooth alterations in 47 specimens of Otaria byronia (Blainville, 1820), from southern Brazilian coast, were analized. Tooth wear and the associated bone pathologies were determined, as well as their percentuals. The main infection was osteomyelitis associated with tooth alterations, such as fractures and attrition, both of them exposing the pulp chamber. Tooth attrition increases with age, favoring fractures and their complications, including osteomyelitis, causing a high frequency of them in specimens presenting more pronounced tooth wear. In one specimen tuberculosis was found in the maxilla, perhaps primarily pulmonary. The high frequency of enamel hypoplasia might reflect cyclic food deficit. Infections and tooth fractures might be related to behaviour, such as fishermen interaction, territorial fighting, and accidents during food capture.

This paper describes a possible fossil egg proceeding from the Bauru Group, Late Cretaceous of Paraná Basin, Brazil. External morphology, dimensions, texture and shell ornamentation examined under electron microscopy show close resemblance to the Recent podocnemidid chelonian eggs. Association with bony material in the outcrop suggests that it is related to a species of Podocnemis. Computerized tomography reveals a high density outer region corresponding to the shell component layers, and successive layers with decreasing density towards the nucleus. An area of high density in the central region may represent remains of an embryo.

A male specimen of Mirounga leonina Linnaeus, 1758 age estimated betvveen 7-8 years old, collected at Santa Vitória do Palmar, Rio Grande do Sul State, soutiiernmost Brazil (32º44'S and 53º22'W) is presented. Ali the skeleton was recovered except the rostral region. It shows an advanced osteomyelitis in the lefl dentary, extending from the synfisis until the middle portion of the body; as well as Scheuermann disease at lumbar vertebrae. Such diseases could explain its presence at that locality, where rt was shot. The bullct was recovered from the rostrum, and might be responsible for death. This is the first vhlually complete skeleton of M. leonina recovered from Brazilian coast.

The studied species were Arctocephalus australis (Zimmermann, 1783) and Arctocephalus tropicalis (Gray, 1872), (five specimens of each one). Anomalies were discussed under the light of theories which relate the ancestry of pinnipeds with the Ursidae; as well as concerning the evolutionary trends supposed for the Otariidae. Pathologies were related to alimentary and reproductive habits.