Papers by Oscar Sanisidro
Methods in Ecology and Evolution, Dec 12, 2022
Dental morphology is a major aspect of ecological and evolutionary studies of both extant and fos... more Dental morphology is a major aspect of ecological and evolutionary studies of both extant and fossil mammalian species. Mammalian dentitions are diverse feeding systems that can be defined through continuous numerical descriptors of the enamel pattern. We developed a comprehensive toolkit to quantify complex occlusal enamel patterns from two‐dimensional images of herbivore mammals, widespread in the scientific literature, in form of three novel enamel complexity descriptors: two‐dimensional orientation patch count (2D OPC), enamel folding (EF), and enamel thickness (ET). Previously proposed parameters such as occlusal enamel index or indentation index are implemented as well. The current method is devised for extracting continuous variables of enamel complexity from macro and microherbivore mammalian species with conspicuous wear facets. A general case study is proposed using two clades within the Family Rhinocerotidae containing species regarded as hypsodonts. The results show that antagonist dental adaptations were achieved through disparate evolutionary strategies in both groups. To test the robustness of this tool under different practical scenarios, other mammalian groups have been evaluated as well. Additional sensitivity analyses include the impact of image size, rotation, or differences in dental wear. Our approach differs from previous 2D techniques in its affordability, versatility, and control over individual regions within each tooth while delivering continuous numerical data. Additionally, the 2D reference images required as input are widespread in the literature and easier to process in comparison to 3D data alternatives.
GSA 2020 Connects Online, 2020
Historical Biology, Apr 6, 2022
Proceedings of the Royal Society B: Biological Sciences
The iconic sabretooth Homotherium is thought to have hunted cooperatively, but the origin of this... more The iconic sabretooth Homotherium is thought to have hunted cooperatively, but the origin of this behaviour and correlated morphological adaptations are largely unexplored. Here we report the most primitive species of Amphimachairodus ( Amphimachairodus hezhengensis sp. nov.), a member of Machairodontini basal to Homotherium , from the Linxia Basin, northeastern border of the Tibetan Plateau (9.8–8.7 Ma). The long snout, laterally oriented and posteriorly located orbit of Amphimachairodus suggest a better ability to observe the surrounding environment, rather than targeting single prey, pointing to an adaptation to the open environment or social behaviour. A pathological forepaw of Amphimachairodus provides direct evidence of partner care. Our analyses of trait evolutionary rates support that traits correlated with killing behaviour and open environment adaptation evolved prior to other traits, suggesting that changes in hunting behaviour may be the major evolutionary driver in the ...
Science
Several scenarios have been proposed to explain rapid net size increases in some early Cenozoic m... more Several scenarios have been proposed to explain rapid net size increases in some early Cenozoic mammalian lineages: sustained and gradual directional change, successive occupation of adaptive zones associated with progressively larger body sizes, and nondirectional evolution associated with branching events in combination with higher diversification potential of the larger lineages. We test these hypotheses in brontotheres, which are among the first radiations of mammals that consistently evolved multitonne sizes. Body-mass evolution in brontotheres mainly occurred during speciation and had no preferential direction. Long-term directional change stemmed from the higher survival of larger lineages in less-saturated herbivore guilds. Our study emphasizes the role of differential species proliferation in explaining the long-term phenotypic trends observed in the fossil record, which are more than an accumulation of steady microevolutionary changes.
• Whether you're networking informally or presenting, think about some simple messages to promote... more • Whether you're networking informally or presenting, think about some simple messages to promote your work.
Geological Society of America Abstracts with Programs, 2020
Journal of African Earth Sciences, 2018
Suidae cranial material is very scarce in South Africa. Here we present a newly found partial cra... more Suidae cranial material is very scarce in South Africa. Here we present a newly found partial cranium recovered from the site of Malapa, South Africa. The cranium is dorsoventrally crushed and does not preserve dentition. We reconstruct the cranium using three-dimensional techniques based on more complete material from Eastern Africa. We assign the specimen to the genus Metridiochoerus and the species ACCEPTED MANUSCRIPT 2 Metridiochoerus cf. M. andrewsi. The partial cranium described here constitutes one of the few of its genus recovered so far in South Africa.
Cidaris, 2010
Información del artículo Nuevas técnicas paleobiogregráficas aplicadas a la Familia Rhinocerotida... more Información del artículo Nuevas técnicas paleobiogregráficas aplicadas a la Familia Rhinocerotidae (Perissodactyla).
Yacimientos Paleontológicos Excepcionales en la Península Ibérica: XXXIV Jornadas de Paleontología y IV Congreso Ibérico de Paleontología, 2018, ISBN 978-84-9138-066-5, págs. 137-141, 2018
Science, Aug 26, 2022
Food webs influence ecosystem diversity and functioning. Contemporary defaunation has reduced foo... more Food webs influence ecosystem diversity and functioning. Contemporary defaunation has reduced food web complexity, but simplification caused by past defaunation is difficult to reconstruct given the sparse paleorecord of predator-prey interactions. We identified changes to terrestrial mammal food webs globally over the past ~130,000 years using extinct and extant mammal traits, geographic ranges, observed predator-prey interactions, and deep learning models. Food webs underwent steep regional declines in complexity through loss of food web links after the arrival and expansion of human populations. We estimate that defaunation has caused a 53% decline in food web links globally. Although extinctions explain much of this effect, range losses for extant species degraded food webs to a similar extent, highlighting the potential for food web restoration via extant species recovery.
Science
Food webs influence ecosystem diversity and functioning. Contemporary defaunation has reduced foo... more Food webs influence ecosystem diversity and functioning. Contemporary defaunation has reduced food web complexity, but simplification caused by past defaunation is difficult to reconstruct given the sparse paleorecord of predator-prey interactions. We identified changes to terrestrial mammal food webs globally over the past ~130,000 years using extinct and extant mammal traits, geographic ranges, observed predator-prey interactions, and deep learning models. Food webs underwent steep regional declines in complexity through loss of food web links after the arrival and expansion of human populations. We estimate that defaunation has caused a 53% decline in food web links globally. Although extinctions explain much of this effect, range losses for extant species degraded food webs to a similar extent, highlighting the potential for food web restoration via extant species recovery.
Fascinating life sciences, 2023
Historical Biology, 2022
Els Casots is one of the richest fossil vertebrate sites of the Vallès-Penedès Basin (Catalonia, ... more Els Casots is one of the richest fossil vertebrate sites of the Vallès-Penedès Basin (Catalonia, Spain). It was discovered in 1989 and excavated briefly during the 1990s, resulting in the recovery of thousands of remains and the erection of several new mammal species. Excavations resumed in 2018 and continue to date. Here we provide updated results regarding the age, stratigraphy, biota and palaeoenvironment of the site. The age of the site is well constrained to ~15.9 Ma thanks to recent bio-and magnetostratigraphic data, thus coinciding with the onset of the Miocene Climatic Optimum (MCO). The stratigraphic succession at the site area indicates lacustrine to palustrine environments with cyclically oscillating water level. There are several fossiliferous layers that have yielded a vertebrate fauna comprising up to 74 different vertebrate species including amphibians, reptiles, birds and mostly mammals. The finding of several articulated partial skeletons indicate that the site records an autochthonous to parautochthonous assemblage. The abundance and completeness of the vertebrate remains together with a well-constrained age and detailed stratigraphic and palaeoenvironmental data, make els Casots a key site for understanding wetland ecosystems in southern Europe during the MCO.
In the present paper, we describe the craniodental remains of three individuals of an amphicyonid... more In the present paper, we describe the craniodental remains of three individuals of an amphicyonid previously determined as <i>Thaumastocyon</i> sp. from the late Miocene (<i>c</i>. 9.1 Ma) pseudokarstic site of Batallones-3. Dentognathic differences in relation to other Thaumastocyoninae enable a new taxon, <i>Ammitocyon kainos</i> gen. et sp. nov., to be defined; it is both the most recent and the most complete member of this subfamily known in the fossil record. The results of our phylogenetic analysis demonstrate that this new form reached the maximum degree of specialization within Thaumastocyoninae, a group that includes the most hypercarnivorous amphicyonid species of the Miocene. The masticatory apparatus of <i>A. kainos</i> is extremely derived, with the loss of the mesial premolars (P3 / P2 and p1–p3) and the third molars (M3 / m3). The robustness of the chin and muzzle is in contrast with the slender and highly sectorial post...
Uploads
Papers by Oscar Sanisidro