ALBERT

Description: 〈span〉〈div〉Abstract〈/div〉We describe a new extinct spiny rat, 〈span〉Proclinodontomys dondasi〈/span〉 n. gen. n. sp. (Rodentia, Caviomorpha, Echimyidae), represented by a noteworthy preserved skull and mandible from the early-middle Pleistocene outcrops at the coastal cliffs of SE Buenos Aires Province (Central Argentina). Phylogenetic analyses allow us to propose that the new species described here and the already known 〈span〉Eurzygomatomys mordax〈/span〉 (Winge) represent a new genus closely related to the living 〈span〉Euryzygomatomys spinosus〈/span〉 and 〈span〉Clyomys laticeps〈/span〉. The new genus differs from 〈span〉Euryzygomatomys〈/span〉 and 〈span〉Clyomys〈/span〉 by having much more procumbent upper incisors, a more developed fossa for the M. temporalis, more flared and laterally expanded zygomatic arches, frontal less markedly expanded posteriorly, jugals much deeper anteriorly than posteriorly, with the dorsal border descending more abruptly posteriorly, smaller orbital cavity, and external auditory meatus relatively smaller and slanted upward and backward. Several features of the new species reflect a higher degree of adaptation to semifossorial habits than those of 〈span〉E〈/span〉. 〈span〉spinosus〈/span〉. The origin of the semifossorial ecomorphotype within echimyids may have been triggered by the expansion of relatively open and arid environments that arose near the Miocene-Pliocene boundary. The record of this new echimyid in Central Argentina indicates that during the early-middle Pleistocene, the southern limit of the geographic range of extinct representatives of the Brazilian lineage of semifossorial echimyids extended farther south than that of their living members.UUID: http://zoobank.org/c30ec1fe-4352-4867-a02f-e0d45c884bfe〈/span〉

Description: 〈span〉〈div〉Abstract〈/div〉Extant medusozoans (phylum Cnidaria) are dominated by forms showing tetraradial symmetry, but stem-group medusozoans of early Cambrian age collectively exhibit tetra-, bi-, penta-, and hexaradial symmetry. Moreover, the developmental and evolutionary relationships between four-fold and other types of radial symmetry in medusozoans remain poorly understood. Here we describe a new hexangulaconulariid, 〈span〉Septuconularia yanjiaheensis〈/span〉 new genus new species, from Bed 5 of the Yanjiahe Formation (Cambrian Stage 2) in the Three Gorges area of Hupei Province, China. The laterally compressed, biradially symmetrical periderm of this species possesses 14 gently tapered faces, the most of any hexangulaconulariid described thus far. The faces are bordered by longitudinal ridges and crossed by short, irregularly spaced transverse ribs. Longitudinally, the periderm consists of three regions that probably correspond, respectively, to an embryonic stage, a transient juvenile stage, and a long adult stage. 〈span〉Septuconularia yanjiaheensis〈/span〉 may have been derived from six-faced 〈span〉Hexaconularia〈/span〉 (Fortunian Stage), which is morphologically intermediate between 〈span〉Septuconularia yanjiaheensis〈/span〉 and 〈span〉Arthrochites〈/span〉. Furthermore, conulariids sensu stricto, carinachitids, and hexangulaconulariids may constitute a monophyletic group united by possession of an organic or organophosphatic periderm exhibiting longitudinal (corner) sulci, a facial midline, and offset of transverse ribs along the facial midline.UUID: http://zoobank.org/01a972aa-aef3-4eef-a9a5-c2d8c3dda615〈/span〉

Description: 〈span〉〈div〉Abstract〈/div〉The earliest known interpreted spatial competition between two species of stromatoporoids, 〈span〉Clathrodictyon〈/span〉 cf. 〈span〉C〈/span〉. 〈span〉mammillatum〈/span〉 (Schmidt, 1858) and 〈span〉Labechia〈/span〉 sp. is found in the Upper Ordovician Xiazhen Formation at Zhuzhai, South China. The interaction between these taxa was initiated by settlement of 〈span〉Labechia〈/span〉 sp. on the surface of 〈span〉Clathrodictyon〈/span〉 cf. 〈span〉C〈/span〉. 〈span〉mammillatum〈/span〉. Distortions of the intraskeletal elements of stromatoporoids represented by abnormally large, wide cysts and thick cyst plates in 〈span〉Labechia〈/span〉 sp. are observed, along with zigzag crumpled distorted laminae and antagonistic behavior of the skeleton in 〈span〉Clathrodictyon〈/span〉 cf. 〈span〉C〈/span〉. 〈span〉mammillatum〈/span〉, indicating syn-vivo interactions. The growth of 〈span〉Labechia〈/span〉 sp. was terminated by the overgrowth of 〈span〉Clathrodictyon〈/span〉 cf. 〈span〉C〈/span〉. 〈span〉mammillatum〈/span〉, possibly reflecting the ecological superiority of 〈span〉Clathrodictyon〈/span〉 cf. 〈span〉C〈/span〉. 〈span〉mammillatum〈/span〉 over 〈span〉Labechia〈/span〉 sp. The observations are interpreted as competitive interaction between stromatoporoids that was most likely facultative, thus most likely occurring by chance, but the interaction allows assessment of different growth behaviors of the stromatoporoid species. Analysis of the interaction provides evidence to improve understanding of the paleoecology and growth behaviors of early stromatoporoids.〈/span〉

Description: 〈span〉〈div〉Abstract〈/div〉Rhenopyrgids are rare, turreted edrioasterid edrioasteroids from the lower Paleozoic with a distinctive and apparently conservative morphology. However, new, well-preserved rhenopyrgid edrioasteroid material from Canada, along with a review of described taxa, has revealed broader structural diversity in the oral surface and enabled a re-evaluation of rhenopyrgid functional morphology and paleoecology.The floor plates in 〈span〉Rhenopyrgus viviani〈/span〉 n. sp., 〈span〉R〈/span〉. 〈span〉coronaeformis〈/span〉 Rievers, 1961 and, 〈span〉R〈/span〉. 〈span〉flos〈/span〉 Klug et al., 2008 are well fused to each other and the interradial oral plate and lack obvious sutures, thereby forming a single compound interradial plate. This differs from other rhenopyrgids where sutures are more apparent. Such fused oral surface construction is only otherwise seen in some derived edrioblastoids and in the cyathocystids, suggesting homoplasy.Our analysis further suggests that the suboral constriction could contract but the flexible pyrgate zone could not. Thus, specimens apparently lacking a sub-oral constriction should not necessarily be placed in separate genera within the Rhenopyrgidae. It also supports rhenopyrgids as epifaunal mud-stickers with only the bulbous, textured, entire holdfasts (coriaceous sacs) anchored within the substrate rather than as burrow dwellers or encrusters.〈span〉Rhenopyrgus viviani〈/span〉 n. sp. is described from the Telychian (lower Silurian) Jupiter Formation of Anticosti Island, Québec, Canada and is differentiated by a high degree of morphological variability of pedunculate plates, broader oral plates, and narrower distal ambulacral zones. Specimens lacking or with obscured diagnostic plates from the Ordovician of Montagne Noire, France, and the Ordovician and Silurian of Girvan, Scotland are also described.UUID: http://zoobank.org/7f81d67f-4155-4719-8a45-b278ad70739d〈/span〉