The Araripe Basin, located in the Northeast of Brazil, contains many fossils. Among these, the gymnosperms stand out, especially species of the fossil taxon Brachyphyllum. It encompasses conifer shoots with helically arranged scale-like, adpressed leaves whose length does not exceed the width. This foliage morphotype was widely distributed during the Mesozoic, and species accommodated in this genus can be attributed to different families if their anatomical characters are taken into consideration. In the Araripe basin, specifically in the Crato and Romualdo formations, Brachyphyllum obesum is frequently found and was attributed to the family Araucariaceae based on leaf epidermal and xylem characters. In this work, we describe a new species from the Crato Formation (Lower Cretaceous), Brachyphyllum sattlerae sp. nov., based on the following morphological and anatomical features: sub-main shoots with lateral branches oppositely disposed and almost exclusively decussately arranged leaves; scarious leaf margins; rugose abaxial leaf surfaces; non-papillate epidermal cells; stomata distributed in longitudinal rows except close to the leaf margins and scarce at the leaf base; stomatal openings obliquely oriented; and hypodermis with a sinuous pattern around the substomatal chamber. Some of these features are distinctive of Araucariaceae, which indicates that B. sattlerae sp. nov. also belongs to this family.

The updated taxonomic revision of the Early–Middle Ordovician graptolites from the eastern Argentine Puna allows describing Sigmagraptus praecursor, Baltograptus extremus, B. geometricus, B. vacillans, Cymatograptus protobalticus, Expansograptus constrictus, E. pusillus, E. similis, and Corymbograptus v-fractus tullbergi for the first time in this region. The analyzed material was collected from the volcano-sedimentary deposits assigned to the Cochinoca-Escaya Magmatic-Sedimentary Complex and exposed at the Muñayoc and Santa Rosa sections, Jujuy Province. This taxonomic analysis confirms the occurrence of 23 taxa in the studied region, from which S. praecursor, B. extremus, and E. pusillus were not previously documented in South America. Additionally, it contributes to the clarification of the faunal graptolite affinities earlier postulated for Northwestern Argentina. Quantitative paleobiogeographic analyses of clusters and principal coordinates were carried out, including the described species and previous certain graptolite assignations for the Puna region, to quantify its faunal affinities with Baltoscandia, Great Britain, North America, and Southwestern China. Finally, our results are discussed and compared with those formerly obtained in paleobiogeographic analyses based on different fossil groups from Northwestern Argentina.

The new coral Heteroamphiastrea loeseri gen. et sp. nov., Family Carolastraeidae, Superfamily Heterocoenioidea, is described from the lower Aptian of the Lindi Region (Tendaguru area) in southeast Tanzania. The new genus is characterised by a cerioid colony type, an underdeveloped septal system with bilateral symmetry defined by a strong main septum with secondary outgrowths and the presence of a marginarium. Overall, this monospecific genus shows skeletal features of the family Carolastraeidae, but like other genera of the family, it shares some morphological features with the families Heterocoeniidae (Heterocoenioidea) and Amphiastreidae (Amphiastreoidea). Heteroamphiastrea gen. nov. exemplifies corals with relatively rare morphology. They are the most controversial Mesozoic corals without consensus on high-rank taxonomy. Heterocoenioidea and Amphiastreoidea have been recently classified into the suborder Heterocoeniina, Amphiastreina or Pachythecaliina, separately or together. Further, they were classified into the Order Scleractinia or into the extinct Order Hexanthiniaria.

The species Carodnia feruglioi and ‘Ctalecarodnia cabrerai' (Xenungulata) were originally described on scarce fragments of teeth from the current Peñas Coloradas Formation at Bajo Palangana (Chubut Province, Argentina). Based on them, the ‘Carodnia horizon’ was named containing one of the oldest native ungulates from South America. However, the type material of these enigmatic xenungulates has remained unknown for more than 80 years, and no updates were performed since their original descriptions. Here, the identification and re-study of the type material, as well as other unpublished specimens from several collections, allowed us to reconstruct part of the dentition of Carodnia feruglioi, describe previously-unknown teeth (e.g., incisors, lower canine, first and second lower molars, and upper molars) and introduce new dental characters for this species. Using length and width ratios of lower dentition (fourth lower premolar, second and third lower molars) as proxies, we compared the metric disparity among the Carodnia species. Based on this study, we provide an emended diagnosis for both the genus and species Carodnia feruglioi and establish comparisons among the six xenungulate documented.

Canids are a very diverse and widely distributed group of carnivorous mammals. These animals entered South America in the early stages of faunistic interchange and later during the Pleistocene. However, the fossil record of these organisms is quite scarce on the continent, particularly in Uruguay. In the present contribution, two skulls associated with mandibles are described. Both materials were referred to as individuals of the Pampas fox Lycalopex gymnocercus, which was supported by morphological and morphometric analysis. These materials were found in late Pleistocene sediments (Sopas Formation) from different localities of northern Uruguay. Some aspects of their systematic and trophic dynamics are discussed. The remains of these animals have previously been listed but never described; thus, this material is the first fossil record reliably determined for this species in Uruguay.

Two upper Permian trackways attributed to the ichnogenus Sukhonopus, regarded as pareiasaurian, have been studied. The longer trackway includes 15.5 locomotor cycles. Statistical analysis of its dimensions indicated that the gait was a lateral-sequence walk close to the slow pace. This conclusion gained additional support through a comparison of dimensions of the two trackways with the glenoacetabular-to-pes length ratio measured on the skeletons of the pareiasaur Deltavjatia. With the sprawling limb posture typical to lower tetrapods, the pace can only be performed with body rocking from side to side, according to the principles of passive-dynamic walking. A natural-sized model of the Sukhonopus producer was built. This model reproduces the passive-dynamic rocking pace, being driven manually by pulling it forward by the rope and simultaneously pushing it from side to side. The passive-dynamic rocking pace of pareiasaurs, proved to be feasible by the model, requires functional differentiation of the hindlimbs and the forelimbs. The former were more appropriate for propulsion, while the latter were more efficient in the generation of the transverse forces required to pump the rocking motion. It is hypothesized that this walking mechanism was associated with an archaic deficiency of nervous and muscular supply of the limbs. Possibly, it was also employed by some other Paleozoic tetrapods. The ichnological evidence of this locomotion technique is the inward turn of the forelimb footprints. The histological evidence is the extensive development in the long limb elements of spongy bone tissue which helps dampen collisions associated with rocking.