Bollettino SPI Vol. 63 (3)

Published in December 2024

Index

  • Barucci A., Ciacci G., Liò P., Azevedo T., Di Cencio A., Merella M., Bianucci G., Bosio G., Casati S. & Collareta A. (2024) – OPEN ACCESS

An explainable Convolutional Neural Network approach to fossil shark tooth identification
pp. 215-227
doi:10.4435/BSPI.2024.15

Abstract

This study explores the capability of Convolutional Neural Networks (CNNs), a particular class of Deep Learning algorithms specifically crafted for computer vision tasks, to classify images of isolated fossil shark teeth gathered from online datasets as well as from the authors’ experience on Peruvian Miocene and Italian Pliocene fossil assemblages. The shark tooth images that are included in the final, composite dataset (which consists of more than one thousand images) are representative of both extinct and extant genera, namely, Carcharhinus, Carcharias, Carcharocles, Chlamydoselachus, Cosmopolitodus, Galeocerdo, Hemipristis, Notorynchus, Prionace and Squatina. We compared the classification performances of two CNNs, namely: SharkNet-X, a specifically tailored neural network that was developed and trained from scratch; and VGG16, which was trained using the transfer learning paradigm. Furthermore, in order to understand and explain the behaviour of the two CNNs, while providing a palaeontologist’s perspective on the results, we firstly elaborated a visualisation of the features extracted from the images using the last dense layer of each CNN, which was achieved through the application of the t-distributed Stochastic Neighbor Embedding (t-SNE) clustering technique. Then, we introduced the explainability method SHAP (SHapley Additive exPlanations), which is a game theoretic approach to explain the output of any Machine Learning model. The results show that VGG16 outperforms SharkNet-X in most scenarios, especially when trained with data augmentation techniques, achieving high accuracy (93%-97%) in tooth classification. In addition, the SHAP heatmaps revealed that the CNNs relied heavily on tooth margins and inner regions for identification, offering insights into the automated classification process. Overall, this study demonstrates that Deep Learning techniques can effectively assist in identifying isolated fossil shark teeth, paving the way for developing automated tools for fossil recognition and classification.

Supplementary Online Material
  • Dorneles V.A.C., Hickman-Lewis K., Barbieri R., Caminiti A.M. & Cavalazzi B. (2024) – OPEN ACCESS

Microbe-mineral interactions in the microstromatolitic crusts of the lacustrine chimneys and volcanic bedrock of Lake Abhe, Republic of Djibouti
pp.  229-244
doi: 10.4435/BSPI.2024.17

Abstract

Utilising a multi-analytical approach, we investigated centimetre-scale domical and tabular microstromatolitic encrustations from Lake Abhe, a hyperalkaline and hypersaline environment in the Afar Rift, Djibouti. We explored the complex interactions between microorganisms and sediments, alongside the preservation potential of microfossils in this extreme setting. Using optical and scanning electron microscopy, we found that the microstromatolitic crusts exhibit both abiogenic and biogenic characteristics and fabrics, influenced by the mixing of lacustrine and hydrothermal fluids and microbial activity. Microcolumnar fabrics, composed of micrite and microsparite laminae, likely formed in calm, supersaturated water conditions and were mediated by microbial mineralisation. Crystalline fabrics, on the other hand, appear to originate from inorganic processes, followed by early diagenetic growth of larger crystals of Mg-calcite. Filamentous cyanobacterial sheaths, preserved within the crusts and often perpendicular to laminations, suggest a photosynthetic growth mode. Extracellular polymeric substances played a key role in microbial carbonate formation by providing nucleation sites for mineral precipitation and anchoring microbes to their substrates. Raman microspectroscopy reveals a concentration of carbonaceous materials within the carbonate matrix; these are closely associated with filamentous sheaths, suggesting their biological origin. The preservation of these biogenic components is also linked to the presence of Mg-bearing silicates, which are likely tied to microbial activity and high pH conditions, consistent with observations in other alkaline lacustrine systems. This study offers insights into microbial carbonate formation and biosignature preservation in extreme alkaline environments, contributing to our understanding of early Earth microbial ecosystems.

  • Serobyan V., Vinn O. & Mottequin B. (2024)

Cyrtospiriferid (Spiriferida) brachiopods from the lower Famennian recovery interval of Central Armenia: insights on biotic interactions and “blisters”
pp.  245-264
doi: 10.4435/BSPI.2024.14

Abstract

The lower Famennian of Central Armenia, which is essentially composed of mixed carbonate-siliciclastic sediments that accumulated on a shallow water platform, yielded a fauna abundant in brachiopods. In order to contribute to the assessment of the diversity in the Famennian recovery interval in this area, two cyrtospiriferid species, Cyrtospirifer sp. C and Pseudocyrtiopsis areniensis n. sp., are described and illustrated. The examined material has been collected from the Aramazdospirifer orbelianusTornatospirifer armenicus Brachiopod Assemblage Zone (coeval to the Palmatolepis crepida Conodont Zone) of three distinct localities (Ertych, Djaravank and Noravank). Among those two species, the former is hereby ascribed to the genus Cyrtospirifer Nalivkin in Fredericks, although the micro-ornament on our specimens differs from those described in other Cyrtospirifer representatives. The presence of Cyrtospirifer sp. C in this brachiopod Zone supports the assertion previously made by the present authors that the genus Cyrtospirifer persisted during the early Famennian in the Lesser Caucasus. The new species Pseudocyrtiopsis areniensis represents the first report of the genus Pseudocyrtiopsis Ma & Day not only in the South Armenian Block but in the entire North Gondwanan margin. This study also includes a discussion on biotic interactions between spiriferides and other organisms, notably cornulitid tubeworms. Moreover, numerous “blisters” are documented in one of the representatives of Cyrtospirifer sp. C.

  • Bona F., Carnevali V. & De Filippis B. (2024)

The Upper Val Seriana (north-western Italy, Bergamo) during MIS3: small mammals as proxy data
pp.  265-273
doi: 10.4435/BSPI.2024.16

Abstract

The Büs di Tri Fradèi cave is located in the municipality of Oltre il Colle (Bergamo province) in north-western Italy. In the cave five main stratigraphic levels occur, of which only one is fossiliferous, corresponding to the Marine Isotope Stage 3 (MIS3). The cave is believed to have served as a nursery for cave bears (Ursus spelaeus), as many remains of females and cubs were found inside, together with those of groundhogs, lacertids and anthropic traces such as flint or cervid antler artifacts. Alongside these, of particular importance for our work is the presence of small mammal remains (Eulipotyphla, Rodentia and Chiroptera), possible preys of tawny owls (Strix aluco), barn owls (Tyto alba) and small carnivores. These finds are fundamental to reconstruct the palaeoenvironment and palaeoclimate surrounding the cave due to the fact that these small mammals occupy strictly specific ecological niches linked to certain environments and climatic conditions. Here, through the Habitat Weighting method and the bioclimatic models, we are able to add important information on the Late Pleistocene palaeoenvironment in north-western Italy using the small-mammal remains from the Büs di Tri Fradèi cave. Our results suggest that, during MIS3, the climate around the cave was cold-temperate (boreal) and the environment was open with limited forested areas.

  • Garassino A., Pasini G., Giusberti L. & Calzoni P. (2024)

A new decapod crustacean assemblage from the lower Eocene of Solteri (Trentino-Alto Adige region, northern Italy)
pp.  275-287
doi: 10.4435/BSPI.2024.18

Abstract

A Ypresian Fossil-Lagerstätte was discovered in the late 1970s in a quarry at Solteri (Trento, northern Italy), but its peculiar fauna, dominated by deep-water bony fishes and subordinate crustaceans and vegetal remains, remained virtually unexplored for decades despite its potential interest. A descriptive analysis of the crustacean fauna revealed the presence of members belonging to the suborders Pleocyemata (infraorder Caridea) and Dendrobranchiata (superfamily Penaeoidea) and to the infraorders Astacida (section Homarida) and Brachyura. Two new genera and species of the infraorder Caridea and one new genus and species of the section Homarida are established herein: Venzia ypresiana n. gen., n. sp., characterized by an elongate and upward directed rostrum with ventral spines; Solteria spinosa n. gen., n. sp., characterized by a short, straight, and spineless rostrum (both Pleocyemata, infraorder Caridea); and Trentastacus levis n. gen., n. sp., characterized by a smooth subcylindrical carapace without grooves or spines (Astacida, section Homarida). The newly established taxa are compared to extant and scarce representatives from the Eocene to further emphasize the uniqueness of this fossil association.

Article
  • Barritta F., Bianucci G., Carone G., Perri E. & Santagati P. (2024)

A Monachinae tooth from the Tortonian of Cessaniti (Calabria, Italy) and some remarks on the fossil record of pinnipeds in the Mediterranean basin
pp.  289-297
doi: 10.4435/BSPI.2024.19

Abstract

The fossil record of Pinnipedia (seals, sea lions and walruses), the second most diverse extant clade of marine mammals after cetaceans, dates back to the late Oligocene-earliest Miocene. Herein, we describe an isolated left premolar of Monachinae indet. (Phocidae) from the Tortonian (Upper Miocene) of Cessaniti, Calabria, Italy. This specimen was collected in unit SH3, where several skeletons of the sirenian Metaxytherium serresii were also found, along with bone remains of an indeterminate physeteroid cetacean, the giraffid Bohlinia, and the proboscidean Stegotetrabelodon. We discuss the fossil record of pinnipeds in the Mediterranean basin, noting that the Cessaniti monachine tooth represents the second undisputed Miocene pinniped record from Italy following the discovery of the Noriphoca gaudini skull more than 150 years ago. Additionally, we observe that all fossil pinnipeds found in the Mediterranean, including the one from Cessaniti, belong to the Monachinae or related basal Phocidae. This fact supports the hypothesis that the Mediterranean was a significant area for the diversification of this pinniped lineage. However, due to the fragmentary nature of the Mediterranean pinniped fossil record, it remains unclear whether the Mediterranean pinnipeds evolved separately over time within this basin or if there were one or more colonization events from the Atlantic, possibly including one following the Messinian Salinity Crisis.

Article
  • Rassegna dell’Attività Sociale – Adunanza dell’Assemblea dei Soci della Società Paleontologica Italiana (SPI), 7 giugno 2024
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