Pucapampella represents an enigmatic genus of non-acanthodian stem chondrichthyans known from the Lower to Middle Devonian (Emsian–Eifelian) of South America, particularly from Bolivia and Peru. Pucapampellids display a mosaic of primitive and derived traits. One of the most distinctive features concerns the structure of the dentition, which is unusual compared to other chondrichthyans. They possess “teeth” that are neither arranged into replacement tooth families (as in most crown chondrichthyans) nor part of dentigerous jaw bones or tooth whorls (as in acanthodians). Instead, their mandibular arches have been described as bearing a single series of sharp “teeth” supported directly by cartilage, without any intervening dermal bone. Paleontological fieldwork conducted in recent years in Devonian strata of the Puno region (southwestern Peru), near Lake Titicaca at an altitude of about 4,200 meters above sea level, has yielded a rich assemblage of new pucapampellid fossils, including exceptionally preserved mandibular remains. These specimens are preserved within phosphatic nodules embedded in grey shales from the upper part of the Chagrapi Formation, which records cyclic successions of dark and grey shales with fine sandstones deposited in a delta-influenced infralittoral marine setting. The upper member, rich in organic matter and phosphatic nodules, indicates episodes of deepening and anoxic conditions. Pucapampellid remains occur in Eifelian-aged levels containing a more diverse vertebrate fauna. Specimens were analyzed using synchrotron PPC-SRµCT, synchrotron μXRF elemental mapping, and paleohistological thin sections. Preliminary results reveal a unique dental architecture unlike any previously described in vertebrates. These findings suggest that the dental structures of pucapampellids represent tooth-like elements that are not homologous to the “true” teeth of other gnathostomes.
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The Late Palaeozoic Ice Age (LPIA) is characterized by glacioeustatic transgressive–regressive cycles, whose signatures are commonly recorded in stratigraphic sequences and associated environmental parameters. Although these glacioeustatic cycles have been documented in Late Carboniferous–Early Permian successions from the Amazonian basins of Brazil, equivalent deposits remain poorly known in the Andean region. This region, particularly Bolivia and Peru, preserves extensive carbonate outcrops from this interval that provide valuable insights into paleoenvironments and faunal assemblages. The Copacabana Formation is composed by warm-water carbonates, evaporites, and open-marine facies. Its broad distribution and cyclicity reflect pronounced climatic and eustatic fluctuations during the LPIA. Studies carry on Puerto Arturo section (Puno, Peru) have revealed abundant early chondrichthyans remains, including Protacrodus, Denaea, Stethacanthus, and Cooleyella amazonensis—preserved as teeth and scales. The relative abundance of these taxa suggests shallow-water conditions (Protacrodus biofacies). In addition, a diverse conodont assemblage, including Idiognathodus, Streptognathodus, Sweetognathodus, and Gondolella, has also been identified. Conodont biostratigraphy and biofacies distributions, based on taxonomic composition and relative abundance per bed, indicate mid-ramp environments characterized by Idiognathodus–Streptognathodus biofacies and outer-ramp settings dominated by Gondolella biofacies. This integrated approach combining sequence-stratigraphic, microfacies, and paleontological analyses provides the first robust paleoenvironmental reconstruction for this interval in Peru, significantly improving regional correlations and revealing new aspects of Palaeozoic diversity in western Gondwana.
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