Lagomorpha as a model morphological system

Due to their global distribution, invasive history, and unique characteristics, European rabbits are recognizable almost anywhere on our planet. Although they are members of a much larger group of living and extinct mammals [Mammalia, Lagomorpha (rabbits, hares, and pikas)], the group is often characterized by several well-known genera (e.g., Oryctolagus, Sylvilagus, Lepus, and Ochotona). This representation does not capture the extraordinary diversity of behavior and form found throughout the order. Model organisms are commonly used as exemplars for biological research, but there are a limited number of model clades or lineages that have been used to study evolutionary morphology in a more explicitly comparative way. We present this review paper to show that lagomorphs are a strong system in which to study macro- and micro-scale patterns of morphological change within a clade that offers underappreciated levels of diversity. To this end, we offer a summary of the status of relevant aspects of lagomorph biology.Brian Kraatz, Rafik Belabbas, Łucja Fostowicz-Frelik, De-Yan Ge, Alexander N. Kuznetsov, Madlen M. Lang ... et al

The hind limb skeleton and cursorial adaptations of the Plio-Pleistocene rabbit Hypolagus beremendensis

Hypolagus beremendensis, a representative of the Archaeolaginae, was one of the most abundant and widespread leporids in the Plio−Pleistocene of Europe. The vast accumulations of skeletal remains from the Polish Pliocene sites (Węże 1, Rębielice Królewskie 1 and 2, and Kadzielnia 1) yielded thousands of bones representing almost all skeletal regions. The detailed hind limb morphology of Hypolagus beremendensisis presented in comparison with five extant leporids (Lepus europaeus, Oryctolagus cuniculus, Pentalagus furnessi, Sylvilagus floridanus, and S. brasiliensis), which represent a wide range of locomotor adaptations. The UPGMA analysis of 98 metric characters places Hypolagus beremendensis next to the leporine rabbits. Hypolagus beremendensis has the os coxae, femur, and talus most similar to P. furnessi, tibia and calcaneus to the leporine rabbits, and the structure of foot to Lepus. The elongation of the foot and tibiofibular segment in relation to the femur indicates an advanced cursorial adaptation and a relatively steep jump. The similarities in the proximal segments (os coxae and femur) between Hypolagus and Pentalagus highlight the conservative morphology of this region in the Leporidae

Lower incisor in zalambdalestid mammals [Eutheria] and its phylogenetic implications

Relationships of the specialized eutherian family Zalambdalestidae (Late Cretaceous, Asia) have long been debated. Beginning with suggestion of Van Valen (1964) and including the recent phylogenetic analysis of Archibald et al. (2001), a possible close relationship of Zalambdalestidae to Glires (Lagomorpha + Rodentia) has been repeatedly suggested (but see Meng and Wyss 2001). One of the characteristics of Glires is the structure of the lower incisor, which is enlarged and open−rooted. An open−rooted incisor has been documented in the oldest known zalambdalestid, Kulbeckia, but structure of this tooth has remained unknown for the Mongolian representatives of this family, Zalambdalestes and Barunlestes. Here we present evidence on the presence of an open−rooted first lower incisor in Zalambdalestes lechei and Barunlestes butleri; we argue, however, that structure of this incisor does not necessarily indicate relationship of Zalambdalestidae to Glires

New data on the Miocene stem lagomorph Eurolagus fontannesi, and its northernmost record

We describe new dental material of Eurolagus fontannesi from the Late Miocene (Early Vallesian, MN 9) lignite beds of Bełchatów A (central Poland), which is the northernmost occurrence of this lagomorph. This material considerably increases the sample size of this rare genus and species. We review the systematic position of Eurolagus and argue that it is not an ochotonid, but represents a terminal taxon of an independently evolved stem lineage of Lagomorpha. The enamel of the molars, here studied for the first time, exhibits a relatively thin decussating external and a radial internal layer, and in general resembles the palaeolagine lagomorphs (Palaeolagus) rather than the archaeolagine leporids (Hypolagus) or advanced ochotonids (Ochotona). The dental wear features of Eurolagus fontannesi indicate that the species was a sylvan mixed−feeder. This agrees with the Bełchatów A paleoenvironment, which is best approximated as the kind of mixed mesophytic forest now encountered in the Caucasus, Iran, and India. The extinction of Eurolagus was probably related to the noticeable faunal change following the increased cooling of the European climate during the Late Miocene. The first indicator of this event can be observed in Bełchatów A, marked by the immigration of Microtocricetus and the absence of Neocometes