D'illa en illa : el viatge d'una rata gegant (Mikrotia magna)

Investigadors de la Universitat Autònoma de Barcelona i de l'Institut Català de Paleontologia Miquel Crusafont han avaluat l'evolució de la mida corporal de Mikrotia magna, una rata gegant que va habitar a l'illa Gargano durant el Miocè tardà. Els resultats mostren que va tenir un clar augment de mida corporal al llarg de la seva evolució insular. Tanmateix, la ferotge competència pels pocs recursos existents a l'illa hagués impossibilitat aquesta mida tan gran. Els investigadors han conclòs que aquesta espècie va tenir un origen en una illa veïna però "va saltar" a l'illa de Gargano en un moment clau que li va suposar la supervivència en l'ecosistema.Investigadores de la Universitat Autònoma de Barcelona y del Institut Català de Paleontologia Miquel Crusafont han evaluado la evolución del tamaño corporal de Mikrotia magna, una rata gigante que habitó en la isla de Gargano durante el Mioceno tardío. Los resultados muestran un claro aumento de tamaño corporal a lo largo de su evolución insular. Sin embargo, la feroz competencia por los pocos recursos existentes en la isla hubiese imposibilitado este tamaño tan grande. Los investigadores han concluido que esta especie tuvo un origen en una isla vecina pero "saltó" a la isla de Gargano en un momento clave que le supuso la supervivencia en el ecosistema.Researchers from the Universitat Autònoma de Barcelona and the Institut Català de Paleontologia Miquel Crusafont have evaluated the body size evolution of Mikrotia magna, a giant rat which dwelled in the paleoisland of Gargano during Late Miocene. The results show a clear increase of body size through its insular evolution. However, the fierce competition over resources would have prevented this aberrant size obtained in the results. That's why researchers have concluded that this species had its origin in a neighboring island but it "jumped" to Gargano in a key moment allowing its survival in the insular ecosystem

Prolagus Pomel, 1853 (Lagomorpha, Mammalia) in the Framework of the Pliocene Faunal Rearrangements in Central Europe

[Abstract] Pliocene occurrences of Prolagus Pomel, 1853 in central Europe represent anomalies out of the peri-Mediterranean area, at that time the core distribution of the genus. Though known for several decades, those materials never underwent a general revision. The detailed analysis and comparison of all available materials performed here revealed two phenotypic entities: 1) Prolagus bilobus Heller, 1936 (Gundersheim localities, Raciszyn 1), for which were defined additional diagnostic characters and ontogenetic patterns of variation (d3/p3 and mandible); and 2) Prolagus sp. (Beremend 26/39), probably a new species. All the available occurrences are dated to MN15b. The morphological trends towards the reduction of p3 entoconid and of enamel folding evidenced in Pliocene Prolagus of western Europe cannot be recognized in coeval central European forms. Evidently, P. bilobus and Prolagus sp. do not pertain to the western European clade, whose separation is known since the early late Miocene. We hypothesize that at least P. bilobus originated from a dispersal of Prolagus from south-eastern regions of Europe rather than from an autochthonous speciation of isolated populations left as a relict after the southward displacement of Prolagus distribution area. The dispersal is likely to be related to the Pliocene global environmental changes during which extensive faunal rearrangements took place in Europe, in particular to those near the early/late Pliocene boundary.[Résumé] Prolagus Pomel, 1853 (Lagomorpha, Mammalia) dans le cadre des réarrangements fauniques du Pliocène de l’Europe centrale. Le peu de données dont nous disposons sur le Prolagus Pomel, 1853 du Pliocène d’Europe centrale représentent des anomalies dans la distribution géographique du genre, qui, à cette époque, est limité à la zone péri-Méditerranéenne. Bien que la présence de Prolagus dans le Pliocène d’Europe centrale est connue depuis plusieurs décennies, de tels matériels n’ont jamais fait l’objet d’une révision générale. Une analyse détaillée et une comparaison de tous les matériels disponibles étudiés ici ont permis d’identifier deux éntités phénotypiques : 1) Prolagus bilobus Heller, 1936 à Gundersheim (plusieurs localités) et Raciszyn 1, pour lequel des caractères diagnostiques additionnels et des modèles ontogénétiques de variation (d3/p3 et mandibule) ont été définis ; et 2) Prolagus sp. à Beremend 26/39, qui représente probablement une nouvelle espèce. Toutes les occurrences disponibles sont datées du MN15b. Les tendances morphologiques vers une réduction de l’entoconide de p3 et une diminution du repli de l’émail, mises en évidence dans les espèces pliocènes de Prolagus d’Europe occidentale, n’ont pas été reconnues dans des formes contemporaines d’Europe centrale. Prolagus bilobus et Prolagus sp. n’appartiennent manifestement pas au clade ouest-européen, dont la séparation est connue depuis le début du Miocène supérieur. Notre hypothèse est qu’au moins P. bilobus trouve son origine dans une dispersion des populations à partir de l’Europe sud-orientale plutôt que, comme on le croyait autrefois, dans une spéciation autochtone de populations isolées, laissées telles des vestiges à la suite du déplacement vers le sud de l’aire de distribution géographique de Prolagus. Cette dispersion est probablement liée aux changements environnementaux à l’échelle globale survenus au Pliocène, et responsables de changements environnementaux globaux pendant lesquels des réarrangements fauniques majeurs ont pris place en Europe, et particulièrement à la transition Pliocène inférieur/supérieur.The study was supported by institutional support RVO67985831 of the Institute of Geology of the Czech Academy of Sciences. CA was supported by: Visiting Professor grant of the President’s International Fellowship Initiative of the Chinese Academy of Science; Spanish Agencia Estatal de Investigación and the European Regional Development Fund of the European Union (CGL2016-76431-P); CERCA Program, Generalitat de Catalunya; Grant to Department of Science, Roma Tre University (MIUR-Italy Dipartimenti di Eccellenza, ART. 1, C. 314-337 L. 232/2016). BMS was supported by Xunta de Galicia (ED481B 2018/046, Axudas á etapa postdoutoral da Xunta de Galicia 2018-Modalidade A)Czech Academy of Sciences, Institute of Geology; RVO67985831Xunta de Galicia; ED481B 2018/04

FOSSIL LAGOMORPHA (MAMMALIA) OF ITALY: SYSTEMATICS AND BIOCHRONOLOGY

Revisions performed in the last 15 years added remarkable novelties to the taxonomy and biochronology of Italian fossil lagomorphs. Several new taxa have been erected basing on new materials and on the revision of old materials. This paper aims to illustrate the state of the art of such researches. The lagomorph diversity in the Italian Neogene and Pleistocene is quite high, accounting 9 ochotonids, 14 leporids, and 3 stem lagomorphs. Among the lagomorph taxa recorded in Italy, quite a high number are insular or continental endemics. The oldest Italian lagomorphs are the insular endemic Paludotona aff. minor, P. etruria and P. minor from the early-middle Turolian of the Tusco-Sardinia palaeobioprovince, and Prolagus apricenicus and P. imperialis from the late Turolian of the Abruzzi-Apulia palaeobioprovince. In the Italian peninsula, lagomorphs are known since the late Turolian (early Messinian) [...

Tooth and Long Bone Scaling in Sardinian Ochotonids (Early Pleistocene-Holocene): Evidence for Megalodontia and Its Palaeoecological Implications

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Body size is a useful character to unravel the biology of fossil taxa and, indirectly, the palaeoenvironment in which they lived. However, the reliability of size proxies is debated, particularly among insular endemics in which large teeth relative to body size have been observed. To shed light on this issue, here we compute statistical models to assess: (i) teeth and long bone scaling and (ii) dentition size evolutionary dynamics in the anagenetic lineage Prolagus figaro-P. sardus from the late Early Pleistocene-Holocene of Sardinia, Italy. Postcranial bones, particularly tibial epiphyses, are shown to be the most suitable parameters for prediction of body mass in Prolagus and other lagomorph taxa. By contrast, p3 should not be used for size reconstructions, whereas m1 width provided the highest correlation with long bones. On the other hand, the postcanine occlusal surface of Sardinian Prolagus (m1 and toothrow area) appeared significantly larger than those of extant lagomorphs, pointing to a higher resistance to tooth wear and a more durable permanent dentition. It seems likely that megalodontia might have evolved in Sardinian Prolagus to cope with the abrasive diet found on islands (food habit hypothesis). Nonetheless, we cannot exclude that other biological features, such as long longevity, could be co-driving forces in this fossil lineage (life history hypothesis). The results achieved throw light on size and scale evolution in lagomorphs, as well as refine the eco-evolutionary responses of small mammals to insular regimes.This work was supported by Consellería de Cultura, Educación e Universidade, Xunta de Galicia, Spain (BM-S, ED481B 2018/046, Axudas á etapa postdoutoral da Xunta de Galicia 2018 – Modalidade A), Visiting Professor grant of the President's International Fellowship Initiative of the Chinese Academy of Science (CA), Spanish Agencia Estatal de Investigación and the European Regional Development Fund of the European Union (CA, CGL2016-76431-P), CERCA Program of the Generalitat de Catalunya (CA), and Grant to Department of Science, Roma Tre University (CA, MIUR-Italy Dipartimenti di Eccellenza, ART. 1, C. 314-337L. 232/2016). Funding for open access charge: Universidade da Coruña/CISUG.Xunta de Galicia; ED481B 2018/04

Comparing the body mass variations in endemic insular species of the Genus Prolagus (Ochotonidae, Lagomorpha) in the pleistocene of Sardinia (Italy)

Prolagus figaro and P. sardus are part of an endemic insular anagenetic lineage that populated Sardinia since the earliest Late Pliocene to Holocene. BM of some populations of these two species was calculated using regression models. The best BM proxies for Prolagus are: femur length, zeugopod measurements and distal humerus diameter. The anagenetic lineage shows a BM increase of ca 20% from the populations of P. figaro (398-436 g) to P. sardus (504-525 g). The trend shown by the size of lower third premolar, even if not directly comparable with BM, is opposite (ca -30% at the transition P. figaro-P. sardus). Compared to P. cf. calpensis, a continental species of similar age, BM of P. figaro is ca +25%. The comparison with the insular endemic P. apricenicus evidenced differences in BM range and timespan required to attain it, due to the different size and palaeogeographical situation of the islands. Insular endemic Prolagus follow the small mammal pattern of Island Rule. Mein's (1983) biphasic model seems applicable to the evolution of P. figaro. A tachytelic phase followed by a bradytelic one seems to characterize also the appearance of P. sardus, at least for dental traits, a process probably triggered by important variations of abiotic and biotic traits of the environment, as indicated by the turnover that marks the onset of the Dragonara subcomplex. The prediction of life history traits and other biological attributes of Sardinian Prolagus using BM should be considered with caution due to the complexity of ecological selective regimes of Sardinia

COMPARING THE BODY MASS VARIATIONS IN ENDEMIC INSULAR SPECIES OF THE GENUS PROLAGUS (OCHOTONIDAE, LAGOMORPHA) IN THE PLEISTOCENE OF SARDINIA (ITALY)

Prolagus figaro and P. sardus are part of an endemic insular anagenetic lineage that populated Sardinia since the earliest Late Pliocene to Holocene. BM of some populations of these two species was calculated using regression models. The best BM proxies for Prolagus are: femur length, zeugopod measurements and distal humerus diameter. The anagenetic lineage show a BM increase of ca 20% from the populations of P. figaro (398−436 g) to P. sardus (504−525 g). The trend shown by the size of lower third premolar, even if not directly comparable with BM, is opposite (ca -30% at the transition P. figaro−P. sardus). Compared to P. cf. calpensis, a continental species of similar age, BM of P. figaro is ca +25%. The comparison with the insular endemic P. apricenicus evidenced differences in BM range and timespan required to attain it, due to the different size and palaeogeographical situation of the islands. Insular endemic Prolagus follow the small mammal pattern of Island Rule. Mein’s (1983) biphasic model seems applicable to the evolution of P. figaro. A tachytelic phase followed by a bradytelic one seems to characterize also the appearance of P. sardus, at least for dental traits, a process probably triggered by important variations of abiotic and biotic traits of the environment, as indicated by the turnover that marks the onset of the Dragonara subcomplex. The prediction of life history traits and other biological attributes of Sardinian Prolagus using BM should be considered with caution due to the complexity of ecological selective regimes of Sardinia

Bone histology of the Late Pleistocene Prolagus sardus (Lagomorpha: Mammalia) provides further insights into life-history strategy of insular giant small mammal

Altres ajuts: CERCA Programme/Generalitat de Catalunya; Consellería de Cultura, Educación e Universidade, Xunta de Galicia (ED481D-2022-013)Fossils provide an excellent opportunity to study and understand the evolution of insular environments free of human-made perturbations. Here, we evaluated the life-history traits and strategy of the extinct insular giant Prolagus sardus (Mammalia: Lagomorpha) by examining microscopically its fossilized bone tissues (osteohistology, skeletochronology, and quantitative geometry). For this task, a complete ontogenetic series of femora retrieved from the Late Pleistocene Grotta della Medusa (NW Sardinia, Italy) were analysed. Our results reveal that: (i) P. sardus' pups were weaned at large size; (ii) the species' maturation was delayed in its life cycle; and (iii) P. sardus lived longer than expected for its size. Hence, the giant P. sardus should have a slow pace of life triggered by the low levels of extrinsic mortality of the insular habitat. On the other hand, bone tissue differences between P. sardus and Ochotona were found in the vascularization, slow- growing bone presence, and cortical and medullary growth trajectories. The results obtained in this study concur with the eco-evolutionary responses described to date in extinct insular lagomorphs, as well as provide new empirical evidence about the phenomenon known as 'insular gigantism' as a pattern of evolution of small-sized mammals in genuine insular ecosystems

Un genoll infectat : el registre patològic més antic documentat en un lagomorf

Llegir les històries de vida dels organismes en els seus ossos o dents és la tasca primordial dels paleontòlegs de vertebrats. Les restes òssies d'espècies passades no únicament ens informen sobre qui eren (taxonomia) o com eren (morfometria), sinó també sobre quines malalties els afectaven (paleopatologia). Així, ocasionalment en alguns ossos fòssils es localitzen marques o estructures anormals que poden relacionar-se directament amb patologies observades en espècies actuals. L'estudi present aborda la patologia més antiga coneguda en una espècie de lagomorf- un ocotònid (Ordre Lagomorpha, Família Ochotonidae, conegudes vulgarment com a piques)-, un avenç que permet enriquir i seguir el traç de la història de les malalties del planeta.Leer la historia de vida de los organismos en sus huesos o dientes es la tarea fundamental de los paleontólogos de vertebrados. Los restos óseos de especies extintas no nos informan únicamente sobre quiénes eran (taxonomía) o cómo eran (morfometría), sino también sobre qué enfermedades les afectaban (paleopatología). Ocasionalmente localizamos marcas o estructuras anormales en algunos huesos fósiles que se pueden relacionar directamente con patologías observadas en especies actuales. El estudio presente aborda la patología más antigua conocida en una especie de lagomorfo- un ocotónido (Orden Lagomorpha, Familia Ochotonidae, conocidas vulgarmente como picas)-, un avance que permite enriquecer y seguir el trazo de la historia de las enfermedades del planeta.Reading the life-history of organisms in their bones and teeth is the main task of vertebrate palaeontologists. Bone remains of extinct species do not only evidence about who (taxonomy) or how (morphometry) they were, but also about the diseases they underwent (palaeopathology). In this way, signs and abnormal structures that can be related directly to pathologies observed in living species are sometimes found in fossilized bones. The present study addresses the oldest known pathology in a species of lagomorph -an ochotonid (Order Lagomorpha, Family Ochotonidae, commonly known as pikas)-, an advance that enriches and tracks the history of the diseases of the planet

Palaeohistology reveals a slow pace of life for the dwarfed Sicilian elephant

Altres ajuts: CERCA Programme/Generalitat de CatalunyaThe 1-m-tall dwarf elephant Palaeoloxodon falconeri from the Pleistocene of Sicily (Italy) is an extreme example of insular dwarfism and epitomizes the Island Rule. Based on scaling of life-history (LH) traits with body mass, P. falconeri is widely considered to be 'r-selected' by truncation of the growth period, associated with an early onset of reproduction and an abbreviated lifespan. These conjectures are, however, at odds with predictions from LH models for adaptive shifts in body size on islands. To settle the LH strategy of P. falconeri, we used bone, molar, and tusk histology to infer growth rates, age at first reproduction, and longevity. Our results from all approaches are congruent and provide evidence that the insular dwarf elephant grew at very slow rates over an extended period; attained maturity at the age of 15 years; and had a minimum lifespan of 68 years. This surpasses not only the values predicted from body mass but even those of both its giant sister taxon (P. antiquus) and its large mainland cousin (L. africana). The suite of LH traits of P. falconeri is consistent with the LH data hitherto inferred for other dwarfed insular mammals. P. falconeri, thus, not only epitomizes the Island Rule but it can also be viewed as a paradigm of evolutionary change towards a slow LH that accompanies the process of dwarfing in insular mammals

First fossil evidence for the advance of replacement teeth coupled with life history evolution along an anagenetic mammalian lineage

In mammals that grow up more slowly and live longer, replacement teeth tend to appear earlier in sequence than in fast growing mammals. This trend, known as 'Schultz's Rule', is a useful tool for inferring life histories of fossil taxa. Deviations from this rule, however, suggest that in addition to the pace of life history, ecological factors may also drive dental ontogeny. Myotragus balearicus is an extinct insular caprine that has been proved to be an excellent test case to correlate morphological traits with life history. Here we show that Myotragus balearicus exhibits a slow signature of dental eruption sequence that is in agreement with the exceptionally slow life history of this species, thus conforming to 'Schultz's Rule'. However, our results also show an acceleration of the absolute pace of development of the permanent incisors in relation to that of the posterior teeth. The rodent-like incisors of Myotragus balearicus erupted early not only in relative but also in absolute terms (chronological age), suggesting that feeding characteristics also plays an important role in dental ontogeny. This is in agreement with ecological hypotheses based on primates. Our study documents a decoupling of the pace of development of teeth in mammals that is triggered by different selection pressures on dental ontogeny. Moreover, we show that Myotragus kopperi from the early Pleistocene (a direct ancestor of the late Pleistocene-Holocene M. balearicus) follows the pattern of first incisor replacement known in living bovids. Hence, the advance in the eruption sequence of the first incisors occurs along the Myotragus evolutionary lineage over a period of about 2.5 Myr. To our knowledge, this is the first fossil evidence of an advance of the emergence of the permanent first incisor along an anagenetic mammalian lineage