Evolutionary trends in dental morphology of the genus Prolagus (Ochotonidae, Lagomorpha) in the Mediterranean islands

Igual que altres taxa de vertebrats, el gènere Prolagusva sofrir modificacions morfo-funcionals importants als ambients insulars mediterranis. El més evident és un increment al·lomètric de la mida general, seguit per altres canvis notables a nivell dentari: increment de la hipsodòncia i del nivell de complexitat de plegament de l'esmalt, i modificacions de les proporcions de diversos trets dentaris. Aquests canvis peculiars es podrien explicar com a adaptacions paral·leles a ambients oberts secs, amb una vegetació molt dura i amb pressions de depredació baixes. Esdevenen a totes les espècies endèmiques de Prolagus diferenciades a ambients insulars mediterranis, fins i tot encara que no tinguin un ancestre directe comú. Algunes formes europees continentals poden mostrar algunes de les característiques esmentades (per exemple, només gegantisme o només presència d'esmalt dentari molt plegat) degut a adaptacions locals alimentàries o ambientals. Només la presència conjunta dels trets dalt esmentats identifica les espècies de Prolagus insulars.As other vertebrate taxa, genus Prolagus undergoes major morpho-dimensional modifications in Mediterranean insular environments. The most evident is an allometric general size increase, followed by other remarkable changes at the dental level: increase of hypsodonty and of enamel folding complexity, modification of relative proportions of some dental features. Such peculiar changes could be explained by a parallel adaptation to dry, open environments with harder vegetation and by a minor predatory pressure. They occur in all the Prolagus endemic species differentiated in insular Mediterranean environments, even if they do not share a common direct ancestor. Some continental European forms, actually, can show some of the listed features (e.g.: giantism only, or highly folded dental enamel only) due to particular dietary/environmental local adaptations. Only the coincident occurrence of the above mentioned characters identifies an insular endemic Prolagus species

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) [...

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

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 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

New insights on Paludotona, an insular endemic lagomorph (Mammalia) from the Tusco-Sardinian palaeobioprovince (Italy, Turolian, late Miocene)

The first vertebrate genus described from the Baccinello-Cinigiano Basin, Paludotona, is here revised almost 6 decades after its original description, with the inclusion of new material. Paludotona is an endemic insular lagomorph that inhabited the Tusco-Sardinian Palaeobioprovince during the late Miocene (Turolian), in the time span between 8.3-6.7 Ma. The continental ancestor of Paludotona remains unknown. We are skeptical about the widely accepted hypothesis of its descent from Lagopsis. The retention of archaic dental features in Paludotona suggests that its ancestor may have been a pre-MN2 European rooted lagomorph. In our opinion the 'modern' characters observed in Paludotona dental elements are the consequence of an evolutionary convergence that was mainly driven by an increased life history triggered by the permanence of an insular environment. We emend the diagnosis of the type species, Paludotona etruria from the Baccinello local biochron (mammal assemblage zone) V1, and erect P. minor n. sp., from Baccinello local biochron V2. The two species differ in size and several dental characters, and do not form a direct phylogenetic lineage. Paludotona minor n. sp. appears to be more closely related to the remains recovered from Baccinello local biochron V0 (referred to P. aff. minor n. sp.) than to P. etruria, which is the temporally closest congeneric species. A few remains referable to the transition of Baccinello local biochrons V1-V2 were ascribed to P. cf. minor n. sp. These results suggest that the Tusco-Sardinian Palaeobioprovince was fragmented into an archipelago. There is no record of Paludotona after the connection of the Tusco-Sardinian Palaeobioprovince and Italian mainland in the Messinian

REVIEW AND NEW DATA OF THE FOSSIL REMAINS FROM MONTE PEGLIA (LATE EARLY PLEISTOCENE, CENTRAL ITALY)

After more than sixty years since its discovery, the fossils from Monte Peglia (late early Biharian, Umbria) are reconsidered in their entirety. The small mammals of Monte Peglia upper and lower levels had been studied in the past, whereas the remains of large mammals of Monte Peglia lower level, stored in several Institutions of central Italy, are described here for the first time. The following taxa have been described: Hystrix refossa, Homotherium latidens, Panthera cf. P. gombaszoegensis, Felis cf. F. lunensis, Canis mosbachensis, Vulpes alopecoides, Meles meles, Pannonictis cf. P. nestii, Mustela palerminea, Ursus cf. U. etruscus; Macaca sylvanus florentinus, Equus altidens, Stephanorhinus cf. S. hundsheimensis, Sus sp., Capreolus sp., Axis eurygonos, Hemitragus cf. H. orientalis, Bison degiulii. Moreover, the list of small mammals of the lower level has been updated with the addition of three new small vertebrate taxa: Rana sp., Myotis sp. (large size), cf. Miniopterus sp. The study of the remains of large mammals of the lower layer indicate the survival of a number of taxa of latest Villafranchian age. If we accept the biochronological correlation of Monte Peglia with the Colle Curti local fauna, its age should be ~1.072 Ma. In this case, it is possible to pinpoint the accumulation of the lower level to the MIS 35/33, as the small mammals confirm the presence of a mixed environment with forested and open spaces and warm temperate climate. The accumulation of the upper level, characterized by taxa typical of open spaces and steppes and a cooler climate, probably occurred during MIS 34/32

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