Search

A state-of-the-art method was developed for repurposing nitrone-containing compounds in the chemosensory field, the ability of the designed molecules to chelate metal cations was evaluated, and their unprecedented solubility in water was confirmed. A facile, rapid, and solvent-free method of synthesizing small molecular mass chemosensors was developed by using a modulative α-aryl-N-aryl nitrone template. α-(Z)-Imidazol-4-ylmethylen-N-phenyl nitrone (Nit1) and α-(Z)-2-pyridyl-N-phenyl nitrone (Nit2) were prepared in 15 min, isolated in less than 60 min with ca. 90% yield, and screened against nine metal cations. Nit1 is a small-molecular-mass compound (188 g mol−1) that is water-soluble and has specificity for sensing Cu2+ with an association constant of K = 1.53 x 1010 and a limit of detection (LOD) of 0.06 ppm. These properties make Nit1 a competitive chemosensor for the detection of Cu2+ in aqueous solution. The nitrone-containing template used in this study is a step forward for new and small chemosensory entities.

The Pediomyiodea has been largely regarded as a Late Cretaceous North American metatherian lineage; however, some studies have suggested that a few South American taxa could be related to this family. Herein, Austropediomys marshalli gen. et sp. nov. from the Itaborai Basin, Brazil (lower Eocene – Itaboraian SALMA), is described. Austropediomys gen. nov. represents the first report of a pediomyoid metatherian in the Paleogene of South America backed by a phylogenetic analysis. Several derived features in the upper molars support its belonging to the Pediomyoidea: presence of accessory ‘conular-like’ structures (here named conuloids) lingual to the conules; supernumerary stylar cusps; asymmetric stylar shelf, with parastylar shelf reduced to a narrow rim in M1; straight centrocrista; short and obliquely oriented prepacrista, which contacts StA in M2–3. The presence of ‘conular-like’ structures lingual to the paraconule and metaconule is identified in Austropediomys gen. nov. and in Late Cretaceous pediomyoids as well, and results in the phylogenetic analysis as a synapomorphy of the Pediomyoidea. Austropediomys gen. nov. is autapomorphyc in the presence of enlarged conuloids on protocristae. The record of a pediomyoid in the Paleogene of South America increases the temporal and biogeographical range of this lineage. Also, our results support the hypothesis that several non-related metatherian lineages dispersed from North to South America via the Caribbean Plate, most probably during the latest Cretaceous, in an island-hopping or sweepstakes model.

The origin of the South American Sparassodonta has always been debated. Current data indicate a North American origin for this group, but no definitive fossil evidence was recovered so far to prove this hypothesis. Herein, Varalphadon janetae sp. nov. is described from the upper Cenomanian and lower Coniacian of southern Utah, which represents the oldest known Sparassodonta. This taxon can be considered to represent Varalphadon as it presents a markedly mesiodistally compressed protocone and M3; small StA, flattened StD, slightly labial contact of the cristid obliqua, labially salient protoconid and lacks StC. It differs from other species of the genus in the smaller size, proportionally narrower protoconal area, paracone slightly more labial than metacone in M3, more labiolingually compressed StD, keeled metaconid and narrower hypoconid and talonid basin. Varalphadon shares with other sparassodonts the presence of vestigial cuspules between StB and StD, flattened and poorly developed StD, absent StC, straight centrocrista, crested conules and an m1 markedly smaller and strongly labiolingually compressed. The phylogenetic analysis recovered Varalphadon as a basal Sparassodonta, corroborating previous studies that considered this taxon as more basal than remaining “Alphadontidae”, which is represented by Protalphadon, Eoalphadon, Alphadon, Albertatherium and Nortedelphys. “Varalphadon” crebreforme is recovered as a Hatcheriformes. The results demonstrate that Metatheria originates in North America during the late Early Cretaceous, with Gondwanan lineages evolving in the Northern Hemisphere during the Late Cretaceous prior to their dispersal to South American millions of years later (late Maastrichtian?). The analysis recovered Metatheria as a Gondwanan invasive lineage.

The sparassodonts were the main mammalian predators during most of Cenozoic in South America. The lower Eocene Itaborai Basin/Formation includes the second oldest fossil records of this group in South America: Patene and Nemolestes. Patene is by far the most abundant sparassodont from this formation, with more than 30 specimens referable to a single taxon, Patene simpsoni. Some specimens recovered from the Quebrada de Los Colorados Formation (former Lumbrera Formation – middle Eocene) in Northwestern Argentina have been also referred to P. simpsoni. In order to test the affinities of Patene and the taxonomy of the Argentinean specimens, we performed a review of the genus. We concluded that the specimens from Northwestern Argentina show significant differences from the Brazilian specimens: smaller size, paraconid more developed; metaconid, entoconid and hypoconid more reduced. As a result, the specimens from the Quebrada de Los Colorados Formation were assigned to a new species, Patene coloradensis. Our phylogenetic analysis supported previous hypotheses that exclude Patene from the “Hathliacynidae”, as the former was recovered as an earlier divergent lineage. The results also supported the hypothesis that Allqokirus australis and Mayulestes ferox from the Tiupampa Basin (El Molino Formation, lower Paleocene – Tiupampian), Bolivia, are the oldest known representatives of the Sparassodonta. The results also supported the monophyly of the Pucadelphyida with the inclusion of the Jaskhadelphyidae and closely related taxa in addition to the Pucadelphyidae + Sparassodonta. The Late Cretaceous, North American Varalphadon was not recovered in our phylogenetic analysis as a representative of the Sparassodonta.Based on our results, the Sparassodonta should be considered, based on the current fossil record, as a South American endemic lineage. doi: 10.5710/AMGH.06.05.2019.3222

Zeusdelphys complicatus is one of the most enigmatic metatherians from the Itaboraí Basin. The type and only known specimen was previously regarded as the upper dentition of Eobrasilia; an M4 of a new taxon; an M3 of a Kollpaniidae (now regarded as a group of “condylarths”); a probable M1 of an incertae sedis taxon; and as an M1 of a Protodidelphidae. Herein, we present a morphological review of the dental structures of Zeusdelphys complicatus, presenting new interpretations and comparing it with other North and South American taxa. We also perform a phylogenetic analysis in order to test the affinities of Zeusdelphys and the validity of most studied characters. The results recovered Zeusdelphys complicatus as more closely related to Hatcheritherium alpha than to any other metatherian. Glasbiidae were recovered as the sister lineage of Protodidelphidae within Didelphimorphia, as true marsupials. Ectocentrocristus was recovered as the sister taxon of Zeusdelphys + Hatcheritherium, as a Hatcheriformes. The analysis recovered this suborder as an independent lineage from Polydolopimorphia, being more closely related to “Alphadontidae”. The affinities with Protodidelphidae are a result of convergent evolution, as Zeusdelphys is more closely related to Hatcheritherium alpha from the Late Cretaceous of North America. The results support a North American origin for Hatcheriformes. The presence of strong sea-level lowstands and islands in the Caribbean Plate during the Late Cretaceous provide valid data to support a faunal interchange between Americas during the latest Late Cretaceous. Based on the results, Zeusdelphys represents a South American early Eocene surviving Hatcheriformes.