{'fraction_non_alphanumeric': 0.016981132075471698, 'fraction_numerical': 0.0, 'mean_word_length': 5.546296296296297, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Histological variation in osteoderms Panochthus sp. and Glyptotherium sp.(Xenarthra: Mammalia) from the Brazilian intertropical region

Glyptodonts are one of the most peculiar mammal groups that inhabited South America during the Pleistocene. Among the main characteristics of the group is the presence of a carapace composed of hundreds of osteoderms, which take on variable forms and external ornamentation. The fossiliferous sites of the Brazilian Intertropical Region (RIB) are rich in glyptodont fossils, of which the osteoderms are the most registered elements, possibly due to their high potential for preservation. Recently, the analysis of histological characteristics has proven useful in the differentiation of genera and species. However, the samples used are still limited and do not consider possible differences among different regions of the carapace. In this work, we evaluate possible histological variations among the osteoderms of Glyptotherium sp. and Panochthus sp. from different regions of the carapace and, based on a larger number of specimens, discuss their implications for the systematics of these genera. We found differences among osteoderms from distinct regions of the carapace for both analysed genera. Within the morphological variation described for the osteoderms of Glyptotherium sp., it is observed that they have more characteristics in common with the species Glyptotherium floridanum than with Glyptodon reticulatus, thus reinforcing that the Glyptodontinae findings in the BIR belong to the genus Glyptotherium sp. The osteoderms of Panochthus share a central region with common characters regardless of the position they occupy in the carapace; the main histological differences among them reside in the layers of compact bone, which show differences even in osteoderms of the same region. Caution is required when the presence of Neuryurus in the RIB deposits based on osteoderms is proposed, as morphological and histological characteristics of some representative of this genus overlap with some altered osteoderms (likely pathological) of the Panochthus sp. studied here.