The examined pathological tibiofibular bone comes from the Goldberg site, a fossiliferous locality of the Nördlinger Ries, Bavaria, southern Germany (Fig. 1). Nördlinger Ries is a circular, shallow depression (22–24 km in diameter), formed by one of the cosmic impacts of a binary stony meteorite, at approximately 14–15 Ma (Abdul Aziz et al., 2008, Arp, 1995, Arp, 2006, Buchner et al., 2013 and Göhlich and Ballmann, 2013). The depression was filled with an enclosed evaporitic soda shallow-water lake, which probably existed for a time span of 0.3 to 2 Ma (Jankowski, 1981). The Goldberg site (among other coeval, neighboring sites as Steinberg-Spitzberg or Wallerstein) is a spring mound of calcareous cool-water tufa (“travertine” hills) that rose at the level of a sublacustrine spring water source (Arp, 1995, Arp, 2006 and Göhlich and Ballmann, 2013). It is assumed that, during certain periods, the spring mounds emerged from the soda crater lake as little islands. Fissures and pockets were formed in the sediments in the subaerial medium, and birds of prey used their crevices for resting or nesting. Their regurgitated pellets were accumulated in the late freshwater stages, forming the fossil vertebrate assemblages. Miotyto montispetrosi Göhlich and Ballmann, 2013, the barn owl described from Steinberg, was the main agent of accumulation (Göhlich and Ballmann, 2013). The vertebrate assemblages contain mostly small vertebrates, including fishes, amphibians, reptiles, birds, and small mammals (Arp, 2006; Heizmann and Fahlbusch, 1983; Rachl, 1983; Ziegler, 1983). The state of preservation of these fossil remains is excellent (Göhlich and Ballmann, 2013 and Heizmann and Fahlbusch, 1983).

The age of the Goldberg site dates back to the Early Astaracian (middle Miocene, MN6), younger than 14.7 Ma (Bolten, 1977 and Lindsay et al., 1989). The paleoclimate of this region at that moment has been interpreted as semi-arid with a mean annual rainfall of 584 ± 252 mm (Böhme et al., 2006 and Heizmann and Fahlbusch, 1983).

A lagomorph right tibiofibular bone is described and examined (Fig. 2 and Fig. 3; Appendix S1). It is curated at the fossil mammal collection of the Staatliche Naturwissenschaftliche Sammlungen Bayerns–Bayerische Staatssammlung für Paläontologie und Geologie (SNSB–BSPG) in Munich (Germany) under number 1966XXXIV 3340. The specimen, as the other fossil remains from Goldberg, was gained from subjecting the blocks of calcareous tufa to dilute acetic acid (Göhlich and Ballmann, 2013).

The specimen was assigned to an adult individual based on the fusion state of its epiphyses. Although the proximal ones are impossible to evaluate due to the abnormal condition, the distal one is completely fused. In Oryctolagus cuniculus Linnaeus, 1758, the growth plate of this latter fuses between the 16th and 28th weeks after birth (Kaweblum et al., 1994 and Masoud et al., 1986), whereas no data is available for ochotonids. The examined specimen is attributed to the family Ochotonidae. Its geological age (middle Miocene, MN6), body size and morphology exclude its classification as a leporid. Actually, leporids settled definitively in Europe only in the latest Miocene (7 Ma), and their presence in European sites before 11 Ma is a matter of debate (Flynn et al., 2014 and López Martínez, 2008). Moreover, the tibiofibula from Goldberg has a total length of 35 mm, and a weight of 126 g based on the transversal diameter of the distal epiphysis (allometric models in Moncunill-Solé et al., 2015). Both dimensions fit with its taxonomic placement among ochotonids (Moncunill-Solé et al., 2016a, fig. 3; Smith et al., 2018). Indeed, in the coeval, neighboring site of Steinberg (Fig. 1), Heizmann and Fahlbusch (1983) reported the presence of two ochotonids: Prolagus oeningensis König, 1825 and Lagopsis verus Hensel, 1856, the latter in larger quantities (Prieto et al., 2009). It is very likely that the pathological specimen from Goldberg pertains to one of these two species. However, as detailed studies and statistics about the postcranial bones of fossil ochotonids are lacking, we refrain to assess a generic taxonomic attribution of the tibiofibula.

The most common methodology for studying paleopathological conditions is the histological analysis (D’Anastasio, 2004, Lyras et al., 2016 and Lyras et al., 2019). Due to its destructive base, however, it is not recommended when the sample size is very small (Anné et al., 2016). Recently, other non-destructive analytical tools (μCT or electron microscopes) allow one to explore paleopathologies without damaging the remains (Anné et al., 2016, Böhmer and Rössner, 2018, Flynn et al., 2013, Foth et al., 2015 and Rothschild and Martin, 2006). Because of the small size of our sample, we decided to evaluate the paleopathology macroscopically and via X-ray microtomography (μCT). The first methodology allows us to identify broadly the main important abnormalities of the bone, whereas the latter provides valuable data about the inner structure of the bone and the microstructural changes. The paleopathological bone was scanned using a phoenix|x-ray nanotom® m (GE Sensing & Inspection Techonologies GmbH, Wunstorf/Hannover, Germany) at the Staatliche Naturwissenschaftliche Sammlungen Bayerns, in Munich. The complete bone was scanned at a voxel size of 0.0164 μm with a voltage of 120 kV and current of 70 μA and a 0.2-mm copper filter (dimensions 566 × 547 × 2326 bytes). A high-resolution μCT of the proximal part of the bone was also conducted (voxel size 0.0053 μm, voltage of 120 kV, current of 60 μA, 0.2 mm copper filter, dimensions 1548 × 2001 × 2364 bytes). Visualization, processing, and analysis of data were performed with software Amira 5.2.0 (Build 531) (Property of 1995–2008 Konrad-Zuse-Zentrum Berlin [ZIB] and 1999–2008 Visage Imaging, Inc.) and Avizo Standard Edition 7.1.0 (Property of 1995–2012 Konrad-Zuse-Zentrum Berlin [ZIB] and 1999–2012 Visualization Sciences Group [VSG], SAS).

For creating the interactive 3D model (Appendix S1), the segmentation tool of AMIRA 5.2.0 was used to differentiate the tibiofibular bone from the modelling clay (used to mount the bone in the chamber of the μCT during scanning). The bone material selected from all slices was converted into a surface component (polygon mesh). Using Avizo 7.1.0, the number of faces of the model was reduced (polygon reduction tool). The surface was saved in Wavefront Format (OBJ). MeshLab v2016.12 (Property 2005–2017 Paolo Cignoni, Visual Computing Lab, and ISTI–CNR) allowed the conversion of OBJ Format into U3D File Format (U3D). This latter file was embedded into a PDF using Adobe Acrobat XI tools (Property 1984–2012 Adobe Systems Incorporated, 2003–2011 Solid Documents, LLC, and 1987–2012 IRIS SA). The protocols described by Ruthensteiner and Heß (2008) and van de Kamp et al. (2014) were followed.

In order to achieve an accurate diagnosis of the studied pathology, comparison with pathologies of extant individuals is paramount. Extant lagomorphs are prone to a large spectrum of diseases and disorders caused by multiple factors (Varga, 2014). They have been mainly described in domestic and farmed specimens of the European rabbit O. cuniculus (Quesenberry and Carpenter, 2004, Richardson, 2000 and Varga, 2014). The most frequent are abscesses (e.g., mandibular abscesses, ulcerative pododermatitis or hock joint infection), ophthalmic, skin, and dental diseases, digestive, neurological and locomotor disorders, as well as cardiorespiratory and urogenital pathologies (Quesenberry and Carpenter, 2004 and Varga, 2014).

Lagomorphs have a very fragile skeleton, which represents only 7–8% of their total weight (Raftery, 2014 and Richardson, 2000). Even though this offers advantages for a rapid escape, the lagomorphs also become more prone to skeletal problems. The most common affections of their musculoskeletal system are dysplastic and degenerative diseases, neoplasia, trauma (leg and vertebral fractures), infection, and pathologies with a nutritional base (Quesenberry and Carpenter, 2004; Richardson, 2000; Turner et al., 2018). In addition, this mammalian group is distinguished by two immunological conditions: lymphopenia and low production of neutrophils (Varga, 2014). This makes them more susceptible to developing infectious diseases and to a high probability of hematogenous spread (Langley-Hobbs and Harcourt-Brown, 2014).

Particularly, wild lagomorphs have fewer dental diseases (feeding on buds and young leaves of bushes), skin diseases (benefits of grooming), and weight problems (not overweight) (Quesenberry and Carpenter, 2004 and Varga, 2014). On the other hand, their natural habitat fosters a range of pathologies that are not common (or have a lower incidence) in domestic individuals (e.g., paratuberculosis, intestinal worms, myxomatosis, or other viral diseases) (Smith et al., 2018 and Varga, 2014). Disabled wild lagomorphs (e.g., as consequence of a chronic diseases or a trauma) have higher probabilities to be caught by a predator (Varga, 2014), whereas most of the domestic animals survive. That explains why literature provides a smaller number of documented medical cases of pathologies in wild lagomorphs, and a large amount in those that are kept in laboratories or private homes.

We compiled and listed in Table 1 data (description, incidence and prognosis) of known pathologies of extant lagomorphs related with osteogenesis and osteolysis.

In the studied specimen, the tibia head (from the tibial plateaus to below the tibial crest, approximately 10 mm) and the most proximal part of the fibula, including the tibiofibular syndesmosis (Fig. 2 and Fig. 3), are the regions affected by the pathology. A local disease affects the metaphysis (the narrow portion between the epiphysis and diaphysis formed mainly by cancellous bone) of the proximal epiphysis and it does not continue along the diaphysis (cortical bone).

A macroscopic examination allows us to identify two differentiated structures in the abnormal region: (1) a jagged-like contour of the metaphyseal border of the tibia (mainly); and (2) a complete rarefaction of the proximal third of tibia and fibula, with the presence of pit holes of different sizes. The proximal margin of the tibia is brittle and discontinuous, full of notches (osteolysis) and projections (osteogenesis) (Fig. 3B–D). In addition to osteophytes and protuberances, an important suprafibular bony projection is located in the most proximal and lateral area of the tibia (Fig. 3B). It ends in a more lateral position than tibia and fibula heads and, over its course from medial to lateral region, it increases in size. In lateral view (Fig. 3D), the projection is oval (measuring approx. 3.5 × 1.75 mm) and very porous. The smooth surface of the proximal part of this projection and the curvature in anterior view point to a possible facet joint, which would accommodate the lateral condyle of the femur. The complete absence of tibial plateaus (osteolysis) exposes the medullary cavity (Fig. 3E). Cancellous bone in the abnormal metaphysis is almost destroyed. Medullary cavity houses an incipient mesh of large bony fibers; one of them is crossing the cavity halfway (Fig. 3E). Externally, the compact bone has a fragile and very porous appearance, with the presence of rounded holes of little to middle size (range: < 0.04 mm–0.4 mm), principally located on the lateral and central region of the tibial head (Fig. 3B–D). In contrast, those of the suprafibular bony projection display elliptic outlines (Fig. 2D). At first glance, the surrounding areas of all these pit holes shows an increase of periosteal bone (periostitis).

Overall, the fibula does not present a major destruction of bone. The proximal epiphysis and diaphysis are complete (Fig. 3B and D). Externally, it has a smooth surface with the presence of a few pores at the posterior and lateral side (Fig. 2 and Fig. 3). Under normal conditions, tibia and fibula are connected by a syndesmosis at the proximal end (Grove and Whitehouse, 1941). The abnormal condition has a strong ankylosis of the two bones, with a reactive bone tissue that covers the most proximal end of the fibula (Fig. 3D). From the lateral view, fibula and tibia are arranged in parallel, and an uncommon curvature is present in the most proximal region (Fig. 2 and Fig. 3). The cause of this abnormal morphology is impossible to identify at simple sight, but it could be consequence of the strong ankylosis (reactive bone growth), a fracture, or both.

The examination of the slices of the μCT reveals the presence of periosteal growth (reactive bone growth, osteogenesis) throughout the pathological region (Fig. 4 and Fig. 5). This growth of new bone is distributed irregularly, showing lacunar-like spots of different size (Fig. 4A–C). These spots or foramina, located inside of new bone formation, could either be a new vascular supply inside the periosteal bone (what is very uncommon) or a cystic-like structure in the cortical new bone layers (what is the most probable, as a secondary phenomenon of a septic process). Periosteal growth is conspicuous in coronal slices of the tibia (Fig. 5A–C), which shows clearly the apposition of two different layers of periosteal bone. The medial bone wall shows only a vertical line, but the lateral one has a different and more complex pattern, full of irregularities and cystic-like structures. Some isolated fragments (Fig. 5A–C) are considered bony micro-sequestra, without the presence of fistulous tracts and cloacae. The presence of periosteal reaction is also evidenced around the regions of the pit holes of the cortical (at different levels) (Fig. 4 and Fig. 5), confirming the macroscopic examination (periostitis). The ankylosis (osteogenesis) of the proximal articulation between tibia and fibula show both bones in a continuum (Fig. 5E). This abnormal adhesion is a common and unspecific reaction of the joint, which is produced after different types of aggressions, including post-traumatic, degenerative, rheumatic or infectious pathologies (Venes, 2001).

On the other hand, there are evidences of different radiological density (rarefaction) between several regions of the metaphyseal pathology (but not present in the diaphysis). Particularly in coronal slices, this effect is marked comparing the medial and lateral cortical bones of the metaphyseal area (Fig. 5A–C). These differences could be related with an overloading of the medial side or with differences between the distribution of the abnormal condition.

Finally, other microstructural changes have been noticed in the pathology. From transversal slices, in the union of the first quarter proximal region of the tibia with the rest, it is drawn a first step of a fistula (abnormal channel that connects internal organs among them or one of them to the outside surface of the body) from in to out (Fig. 4B). Besides, the images allow us to observe several lines related with traumas or fractures. The first one is a healed fracture oblique line in the upper fibula, which is observed in coronal and sagittal slices (Fig. 5D, F–G). The second one is located at the level of the fibula too, following a proximo-distal axis, but its outline and surrounding bone highlight that, with all likelihood, it occurred postmortem (Fig. 5F). The slices of the inner region of the tibial diaphysis show the appearance of the cancellous bone with porosity (Fig. 5A–C). However, it is much less specific than the injuries that are present in the cortical bone.

In the studied specimen, osteogenesis and osteolysis are the two principal processes observed in the abnormal bony region. Infectious diseases (bacterial, viral or fungal) and neoplastic disorders (osteosarcoma or osteochondroma) are the two main conditions that show both processes, whereas osteonecrosis solely related to osteolysis is excluded (Table 1). In vivo, the differentiation between the first two pathological groups is problematic (Raftery, 2014). It is obtained combining histopathological examinations and biopsies, assessment of growth patterns, consistency, exudations, and X-ray images (Harcourt-Brown and Chitty, 2014). In our case, we will try to have to rely on evidences to exclude one of the two possible causes.

Neoplasias are uncommon in rabbits and hares (particularly in juveniles and young adults), especially those that affect the limbs (Tinkey et al., 2012 and Varga, 2014). Osteochondromas are generally pedunculated injuries, not associated with bone destruction, and with a very low incidence in lagomorphs (Meuten, 2017 and Suckow et al., 2012). Osteosarcomas mainly affect maxilla and mandible in lagomorphs (Manning et al., 1994). They have a distinguishable morphology (spicular) and generally never cross joints (adjacent bones are not affected) (Meuten, 2017). These specific traits (morphology, location, etc.) and their low incidence (Table 1) allow us to rule out neoplastic conditions as the cause of the examined tibiofibular abnormality.

As for infectious diseases, epithelial and dermic abscesses are frequent in lagomorphs. The diagnosis in vivo of the affected limbs includes the observation of palpable masses, lameness, hair loss, and cellulitis (Oglesbee, 2012). When an infectious disease affects bones, osteolysis and periosteal reaction are observed (Richardson, 2000). Osteomyelitis, tuberculosis, and septic arthritis are the most common bony infections in lagomorphs (Table 1). The first two entail an inflammation of the bone, whereas the latter is an infection of the joint (Oglesbee, 2012 and Richardson, 2000). Tuberculosis can be excluded because it has a low incidence and it is not associated with a periosteal reaction (Table 1), a process observed in the examined tibiofibula (Barthold et al., 2016 and Rogers and Waldron, 1989). In addition, the origin of the Mycobacterium tuberculosis complex (the group of bacteria that includes Mycobaterium bovis, the main agent of tuberculosis in rabbits), is dated back to only 40,000 years ago (Manning et al., 1994 and Wirth et al., 2008).

Osteomyelitis and septic arthritis affect different bony regions, although they are often difficult to distinguish, because one can trigger the other. Osteomyelitis, related with bone lysis and periosteal reaction, causes a heat, swollen, and painful limb. Septic arthritis is an inflammatory disease characterized by ticked periarticular tissues, synovial effusion, osteolysis, irregular joint space, erosions and periarticular osteophytes, and is associated with lameness, decreased range motion of the joint, soft tissue swelling, heat, and pain (Oglesbee, 2012). In the examined specimen, the macroscopic and radiologic analyses (periosteal reaction, ankylosis and lysis) and the local affection of the juxta-articular region are consistent with the diagnosis of a septic arthritis of the knee (Table 1). We cannot evaluate the kind of affection that would be presented in the femoral condyles, but the radiological patterns of the studied individual put aside the diagnosis of degenerative joint disease (progressive deterioration of the articular cartilage) and post-traumatic joint disease.

In septic arthritis, the bacterium reaches the synovium of the bone/joint using two possible ways: (1) direct, primary (infection of the bone, joint or surrounding soft tissues, e.g., an osteomyelitis in the metaphysis of a long bone), and (2) indirect, secondary (hematogenous spread, bacteremia or septicemia, from a primary focus of infection). In the former case, several conditions can be susceptible of bone infection: trauma (fracture or fissure), puncture/penetrating wounds (seeds or pieces of hay that penetrate the skin), or bite wounds (fights with other rabbits or predators) (Oglesbee, 2012 and Varga, 2014). Moreover, skin infections (ulcerative pododermatitis, nail-bed infection, abrasions or furunculosis) can extend to underlying soft tissues, bones or joints (Oglesbee, 2012 and Richardson, 2000). It is also known that primary infections could spread via bloodstream or lymph causing secondary infections in any other organ system (especially on thoracic cavity or abdomen) (Varga, 2014).

The assessment of the patterns of the injury, the microscopical analysis of the abnormal area, as well as the affected body region (hindleg) allow us to consider that, with all likelihood, the septic arthritis was a peri-articular joint reaction to a violent mechanism as a bite. Thus, the entrance of the bacterium was direct (primary focus of infection). Bite wounds in lagomorphs could be consequential of combats among different individuals (intraspecific competition, especially among males) or could be inflicted by predators when lagomorphs try to escape or avoid their attack (e.g., carnivoran such as canids) (Varga, 2014). For the moment, we cannot identify the potential causative species.

The bacteria related with septic arthritis in lagomorphs are pyogenic ones, including staphylococci (e.g., Staphylococcus aureus), Pasteurella multocida, Pseudomonas, Fusiformis, and anaerobic ones (Nade, 2003 and Oglesbee, 2012). Varga (2014) described that the most common bacterium isolated from infected bite wounds in lagomorphs is P. multocida, a Gram-negative coccobacillus of small size.

The strong necrotic and osteogenic changes observed in the tibiofibular bone highlight that the pathology certainly had a large impact on the life of the individual, affecting locomotion, feeding or predator escaping, among other vital activities. Abscessed joints are swollen and very painful, and the individual limps and keeps immobile, avoiding moving (Oglesbee, 2012; Praag et al., 2010 and Varga, 2014). The infection can lead to a permanent disability of the articular movement, preventing feeding or safeguarding. Additionally, the locomotive reduction entails a poor blood circulation, and consequently a decrease of the vital conditions (van Praag et al., 2010). Infections have a very poor prognosis in this mammalian group (Table 1), and a generalized spread of the infection (septicemia) can cause a rapid death (Richardson, 2000 and Suckow et al., 2012).

In natural environments, the decreased mobility and the poor vital conditions of individuals with septic arthritis make them easy targets for predators (Varga, 2014). Indeed, the vertebrate assemblages from Goldberg are mainly the result of the piling of pellets regurgitated by birds of prey (Göhlich and Ballmann, 2013). In this regard, the cause of death of the concerned ochotonid is probably related to predation, and not a direct consequence of the infection (e.g., septicemia).

The study of paleopathologies is indeed a quite new field of research. However, there is an important scarcity of evidences of paleopathological conditions in lagomorphs and other small mammals compared with large ones. This fact may be consequence of several reasons. The study of small mammals is based on dental remains, which are the most numerous and best preserved parts of small mammals as fossils (sometimes the only to be preserved). Skeletal elements are less likely to be preserved and are less studied, as taxonomy is based mainly on teeth. In addition, dental diseases have a minor incidence in wild animals (Varga, 2014). On the other hand, extinct and extant lagomorphs are considered small/medium mammal species (70–300 g) (Smith, 2008). Their little dimensions could be a factor that hampers the observation, assessment, and diagnosis of abnormal bony conditions (Luna et al., 2017). Moreover, lagomorphs show a fast life history (marked by an earlier reproduction maturity, large litter size, and short lifespan, some of them do not live more than one or two years) (Promislow and Harvey, 1990 and Smith, 2008). Thus, their interaction period with the environment is lesser than in large mammals, as well as the probability of suffering some pathological disorders. In the wild, injured or sick individuals are at increased risk of predation (Varga, 2014). Although they could survive, this will depend on their ability as individual (for feeding and avoiding predators) and the biological traits of their species (social behavior). In general, the presence of paleopathological changes (e.g., fused fracture or chronic pathologies) highlights survival of the individual for a certain time period (Luna et al., 2017 and Mariani-Costantini et al., 1996). Accordingly, Mariani-Costantini et al. (1996) proposed that paleopathologies will be more frequent in large powerful species, with a complex social behavior and remarkable defensive abilities (Adams, 1990), conditions quite contrary to the biology of lagomorphs (Smith et al., 2018).

Studies of paleopathological dental or maxilla/jaw remains of lagomorphs are not available in the literature. Instead, there are citations of probable abnormal conditions. Crusafont et al. (1955) erected the species Heterolagus albaredae Crusafont et al., 1955 (Molí Calopa, Spain, MN3b) based on an unnoticed pathological specimen of Lagopsis penai Royo, 1928 with “wrongly” inclined lower molars (López Martínez, 1989). Berzi (1967) described an unusual possible pathological condition (a diastema between the third and fourth lower premolars) in Prolagus savagei Berzi, 1967 (Italy, late Pliocene, MN16a). López Martínez and Thaler (1975) argued that this condition was consequence of anomalous fossilization. López Martínez and Thaler (1975) noticed that, in the material of Prolagus crusafonti López Martínez, 1975 (in López Martínez and Thaler, 1975) from Can Poncic (Spain, early late Miocene, MN9), there is a high incidence of teeth with an irregular occlusal surface. They associated this condition on teeth with a necrotic process affecting the mandibular condyle. That part of the jaw is not preserved in the mentioned material. López López Martínez (1989, p. 108), p. 108) refers to a high number of pathological teeth of Titanomys calmaensis Tobien, 1974 from La Chaux-de-Fonds (Switzerland, MN2a) (Tobien, 1974, figs. 81, 84, 85, 87) supposedly characterized by divergent axes of the tooth shafts. However, the figures in Tobien (1974, figs. 81, 87) show a minimally inclined shaft that makes us refrain to define it as pathological. At any rate, the incidence of lagomorph paleopathological teeth is minimal in Eurasian collections and they have been limited mainly to fractures or growth out of axis probably due to feeding accidents and wrong position during eruption respectively. The evidence for those conditions is a bizarre or unusual occlusal surface pattern. The individuals in which those conditions were observed were adults and apparently lived with the pathological condition without being seriously affected (CA, pers. obs.).

The first attempt to diagnose pathological conditions in fossil lagomorphs was based on postcranial elements of P. sardus, the middle Pleistocene–Holocene endemic ochotonid of Corsica and Sardinia. Zoboli (2003) and Zoboli et al. (2018) reported abnormal conditions in Sardinian materials, mainly related to traumas and infections, but secondarily to tumors and malnutrition conditions. Congenital diseases, on the other hand, were completely excluded. The authors also noticed that the incidence of diseased remains was less than 2%. Their results are in line with the several studies focused on the description of abnormal conditions in insular mammals (Adrover, 1972, Dermitzakis et al., 2006, Jordana et al., 2011, Lyras et al., 2016, Lyras et al., 2019, Maempel, 1993 and Palombo and Zedda, 2016). Also, in those cases, pathological conditions are mainly related to nutritional (long-term malnutrition, deficiency of some elements or vitamins) or environmental (traumatic or degenerative) causes. The prevalence of pathological specimens in those samples ranges from 0.2 to 10%.

Insular environments are characterized by a lower predation pressure than in mainland ones (Sondaar, 1977). Specially in small mammals, this different selective pressure entails a modification of the life history, such as a longer lifespan (Palkovacs, 2003). In this regard, Moncunill-Solé et al., 2015 and Moncunill-Solé et al., 2016a noticed a longer lifespan in Prolagus apricenicus Mazza, 1987 than in mainland extant ochotonids. As bigger animals live longer, it is possible that also the insular endemic Sardinian chronospecies Prolagus figaro López Martínez, 1975 (in López Martínez and Thaler, 1975) and P. sardus, which weighed almost double than coeval congeneric species (Moncunill-Solé et al., 2016b), had a longer lifespan, in spite of the fact that it coexisted with the Sardinian dhole Cynotherium sardoum Studiati, 1857, which was a small prey hunter (Lyras et al., 2006). Thus, due to the longer lifespan of insular lagomorphs, it is not surprising that most of the evidence of paleopathological conditions in lagomorphs have been recorded in insular forms (Zoboli, 2003 and Zoboli et al., 2018).

To sum up, the finding of an extinct mainland ochotonid showing a pathological condition is a rarity. Thus, the abnormal tibiofibular bone from Goldberg site is exceptional. The diagnosis, etiology, and cause of death of the individual that are provided here give us clues about the paleobiological traits of mainland lagomorph species (e.g., survival capacity or circumstances of death) and their role in the ecological habitats (e.g., interaction between species and environments). Although lacking detailed statistical studies, the prevalence of paleopathological conditions in mainland ochotonids is lower than in populations of insular endemics.