Hypolagus balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 (Mammalia: Leporidae): new data from the Neogene of Eivissa (Balearic Islands, Western Mediterranean) Author Cardona, Josep Quintana Author Moncunill-Solé, Blanca text Geodiversitas 2014 2014-06-27 36 2 283 310 http://dx.doi.org/10.5252/g2014n2a4 journal article 6399 10.5252/g2014n2a4 07c13700-9a35-4ec4-9dfe-d994f3ea7ade 1638-9395 4538423 Hypolagus balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 DESCRIPTION Cranium (IPS-41726; Fig. 2 ; Tables 1 , 2 ) Relatively small, badly preserved, without teeth. The body of maxilla is partially preserved. The two maxillas show the alveolus of P2, P3, P4 and M1. The M2 alveolus is only partially preserved. Only the facial tubercles of the two zygomatic archs are preserved. The maximum distance between the ventral surface of the facial tubercle and the dental alveolus is very small. The two major palatine foramina are situated very close to the anterior side of the choana. The posterior side of the palatine fissure is situated at the same level as the mean length of P2. The frontal bones are partially preserved. The supraorbital caudal notch appears shallow. The posterior zone of the zygomatic process (and the supraorbital caudal notch) is only little developed, which is likely due to the poor preservation of this part of the cranium. Though both orbits are badly preserved, the distance between the zygomatic process of the frontal bone and the dorsal side of the facial tubercle suggests that the orbits of H. balearicus are proportionally smaller than those of Oryctolagus cuniculus (Linnaeus, 1758) . Left incisor I1 (IPS-61674; Fig. 3H ) The linguoventral and medioventral margins show a well rounded outline. The central part of the ventral margin is slightly concave. The dorsal face is crossed by a rather wide V-shaped groove.It shows a depth of 18% in relation to the dorso-ventral width of tooth. Labial lobule with a well rounded outline, wider than the lingual lobule, which is acuter and narrower. The enamel is only present on the dorsal half of the tooth. Left premolar P2 (IPS-61601; Fig. 3D ) The paraflexus has a depth equivalent to the 36% of the anteroposterior tooth length. The lagiocone is formed by two lobes with similar contour, separated by a mesoflexus that shows a depth that equals 1/3 of the paraflexus length and 12% of the anteroposterior length. The metaflexus forms a very slight concavity. The hypercone antero-lingual contour is genuinely rounded, without hypoflexus. TABLE 2. — Length (in mm) of the superior toothrow of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 compared with other leporids. Data sources: 0 , Quintana (2005); 1 , Fostowicz-Frelik (2007a); 2 , Fostowicz-Frelik (2003); 3 , Sych (1965) ; 4 , White & Morgan (1995) ; 5 , Averianov et al. (2000).

Taxon	n	Max.-min.	Mean	SD	Source
Hypolagus furlongi Gazin, 1934	–	–	11.50	–	4
Hypolagus edensis Frick, 1921	1	–	11.70	–	4
Sylvilagus audubonii (Baird, 1858)	18	13.58-10.66	12.04	0.79	0
Sylvilagus nuttallii (Bachman, 1837)	2	12.39-11.79	12.09	0.42	0
Sylvilagus floridanus (J. A. Allen, 1890)	1	–	12.31	–	0
Bunolagus monticularis (Thomas, 1903)	2	13.03-11.75	12.39	0.90	0
Hypolagus balearicus	1	–	13.35	–	–
Oryctolagus cuniculus (Linnaeus, 1758)	17	16.95-11.92	13.84	1.27	0
Sylvilagus brasiliensis (Linnaeus, 1758)	2	14.24-13.66	13.95	0.41	0
Lepus saxatilis F. Cuvier, 1823	5	19.23-13.69	15.27	2.24	0
Nesolagus netscheri (Schlegel, 1880)	1	–	15.54	–	0
Lepus capensis Linnaeus, 1758	1	–	15.67	–	0
Lepus californicus Gray, 1837	6	16.63-15.11	15.91	0.68	0
Hypolagus gidleyi White, 1988	6	16.60-15.20	16.00	0.56	4
Nesolagus timminsi Averiánov, Abrámow & Tikhonov, 2000	–	–	16.10	–	5
Pronolagus crassicaudatus (I. Geoffroy, 1832)	1	–	16.17	–	0
Lepus granatensis Rosenhauer, 1856	2	18.39-14.58	16.19	1.97	0
Hypolagus balearicus	1	–	16.20	–	–
Lepus castroviejoi Palacios, 1976	2	16.85-16.43	16.64	0.30	0
Hypolagus brachygnathus (Petényi, 1864)	1	–	16.80	–	3
Hypolagus brachygnathus	7	18.90-16.80	16.93	–	3
Hypolagus brachygnathus	2	–	17.25	–	3
Hypolagus beremendensis (Petényi, 1864)	5	18.00-16.90	17.30	0.43	2
Hypolagus schreuderae Teilhard de Chardin, 1940 5		18.00-17.00	17.30	0.44	2
Hypolagus schreuderae	5	18.00-17.00	17.30	–	3
Hypolagus petenyii Čermák & Fladerer in Čermák, 2009	1	–	17.40	–	1
Hypolagus brachygnathus	6	18.80-17.10	17.40	–	3
Hypolagus brachygnathus	2	–	17.40	–	3
Hypolagus brachygnathus	8	18.70-16.90	17.51	–	3
Hypolagus beremendensis	18	18.60-16.60	17.63	0.61	2
Hypolagus petenyii	12	–	17.70	0.70	1
Hypolagus petenyii	7	–	17.70	0.80	1
Hypolagus petenyii	3	–	17.70	–	1
Hypolagus petenyii	1	–	18.00	–	1
Hypolagus brachygnathus	2	–	18.40	–	1
Hypolagus beremendensis	2	–	18.40	–	2
Hypolagus brachygnathus	2	–	18.40	–	3
Pentalagus furnessi (Stone, 1900)	–	–	18.47	–	0
Hypolagus gromovi Gureev, 1964	4	19.60-18.90	19.20	–	2
Hypolagus gromovi	5	20.10-19.00	19.60	–	3
Nuralagus rex Quintana, Köhler & Moyà-Solà, 2011	20	25.85-18.81	23.60	2.03	0

P3-M2 (IPS-61661, 61662, 61665 [ Fig. 3E ]; IPS-61663 [ Fig. 3F ]; IPS-61664, 61666) Variable hypoflexus morphology, but with no more than three lobules on the anterior margin. The hypoflexus enters up to half of the tooth approximately. Posterior side of the hypoflexus only slightly undulated. Mandible – IPS-26592A: mandibular fragment with p4, m1 and m2 ( Fig. 3C ); – IPS-26592B: left/right mandibular fragment; – IPS-41727: incomplete right mandible ( Fig. 4 ); – IPS-26590: incomplete left mandible; – IPS-26591: left mandibular fragment ( Table 4 ). FIG. 2. — Skull of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 from Ses Fontanelles (IPS-41726) in dorsal ( A ), ventral ( B ) and lateral views ( C ). Scale bar: 10 mm. The retroalveolar foramen is small with an elliptic outline. The mandibular ramus is 134° inclined in relation to the dorsal side of the mandibular body ( Table 3 ). The posterior side of the mental foramen is in line with the anterior side of p3. Remarks. The inclination of the mandibular ramus appears to be related to the cranium length. The inclination is similar in H. balearicus and other leporids with a proportionally short skull ( Table 3 ). FIG. 3. — Dentition of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 : A , right p3 (IPS-61602); B , left p3 (IPS-61603); C , p4-m2 (left mandible IPS-26592A); D , left P2 (IPS-26583); E , right P3-M2 (IPS-61665); F , left P3-M2 (IPS-61663); G , left i1 (IPS- 61675); H , left I1 (IPS-61674). Scale bar: 1 mm. TABLE 3. — Inclination of the mandibular ramus of H.balearicus Quintana,Bover,Alcover,Agustí & Bailon,2010 in relation to other leporids.

Taxon	n	Max.-min.	Mean	SD
Pentalagus furnessi (Stone, 1900)	1	–	130°	–
Nesolagus netscheri (Schlegel, 1880)	1	–	132°	–
Nuralagus rex Quintana, Köhler & Moyà-Solà, 2011	1	–	134°	–
Hypolagus balearicus	1	–	134°	–
Poelagus marjorita (St. Leger, 1932)	1	–	135°	–
Oryctolagus cuniculus (Linnaeus, 1758)	6	143°-136°	139°	3.14
Lepus capensis Linnaeus, 1758	1	–	143°	–
Lepus saxatilis F. Cuvier, 1823	1	–	145°	–
Bunolagus monticularis (Thomas, 1903)	1	–	150°	–

Left incisor i1 (IPS-61675; Fig. 3G ) Tooth with a rounded trapezoidal outline. The enamel only covers the ventral side of the tooth. Right premolar p3 (IPS-61602; Fig. 3A ) and left premolar p3 (IPS-61603; Fig. 3B ) Tooth with trapezoidal outline. Little pronounced or shallow anteroflexid and absent paraflexid. The anteroconid shows a rounded, slightly sharpened outline. V-shaped protoflexid, with a depth equal to 13.5%-16% of the total width of the tooth. The hypoflexid relative depth is about 48%-52%; undulation of the flexid is not observed; the mesial side of the hypoflexid shows, sometimes, a marked convexity; distal and mesial walls run almost parallel. Lingual side with rounded outline, slightly wider (anteroposterior direction) than the medial zone of the hypoflexid; labial anteroconid with trapezoidal outline. Lingual anteroconid with straight or convex contour. FIG. 4. — Right mandible of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 (IPS-41727) in lateral ( A ) and dorsal views ( B ). Scale bar: 10 mm. Remarks. The two p3 from Eivissa differ in size and in the morphology of the hypoflexid. There are considerable differences in size between the Eivissa p3 and that of Caló d’en Rafelino (Mallorca) ( Quintana et al. 2010 : fig. 3). However, the morphological differences between the p3 of the two island populations are little significant, and consist basically in the absence of undulation on the hypoflexids of the p3 from Eivissa. p4-m2 (IPS-61667-61673; Fig. 3C ) Hypoflexid with smooth or slightly undulated anterior and posterior margins. The lingual extreme of the hypoflexid is curved towards the anterior margin of the tooth.This curvature increases progressively from p4 to m2. The enamel of the posterior margin of the hypoflexid is extremely thin, similar to that on the anterior margin of the trigonid. The enamel disappears on the lingual face on both trigonid and talonid. Humerus (IPS-41728, left incomplete humerus, TABLE 4. — Mandible height (in mm) of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 compared with other leporids. Data sources: 0 , Quintana (2005); 1 , Fostowicz-Frelik (2003); 2 , Fostowicz-Frelik (2007a); 3 , Sych (1965) ; 4 , Fladerer & Fiore (2002).

Taxon	n	Max.-min.	Mean	SD	Source
Oryctolagus cuniculus (Linnaeus, 1758)	5	13.30-11.01	12.02	0.85	0
Hypolagus balearicus	2	13.90-11.84	12.87	1.45
Hypolagus brachygnathus (Petényi, 1864)	1	–	13.20	–	2
Lepus granatensis Rosenhauer, 1856	1	–	13.58	–	0
Hypolagus peregrinus Fladerer & Fiore, 2003	6	14.60-12.50	13.60	–	4
Hypolagus brachygnathus	4	14.40-14.20	14.33	–	3
Hypolagus brachygnathus	13	16.30-14.00	14.49	–	3
Hypolagus petenyii Čermák & Fladerer in Čermák, 2009	1	–	14.50	–	2
Hypolagus petenyii	24	–	14.50	0.90	2
Hypolagus petenyii	13	–	14.50	0.60	2
Hypolagus beremendensis (Petényi, 1864)	16	15.90-13.00	14.60	0.90	1
Hypolagus petenyii	68	–	14.60	0.90	2
Hypolagus beremendensis	14	16.20-14.00	14.82	0.74	1
Hypolagus brachygnathus	14	15.70-14.60	14.90	–	3
Hypolagus beremendensis	1	–	15.00	–	2
Hypolagus brachygnathus	4	–	15.00	0.40	2
Hypolagus brachygnathus	1	–	15.10	–	3
Hypolagus brachygnathus	9	15.30-14.90	15.12	–	3
Lepus europaeus Pallas, 1778	32	16.70-14.00	15.18	–	3
Hypolagus brachygnathus	14	15.90-14.80	15.21	–	3
Hypolagus beremendensis	3	15.61-14.55	15.24	–	1
Hypolagus brachygnathus	5	15.80-14.80	15.40	–	3
Hypolagus beremendensis	2	15.90-15.00	15.45	–	1
Hypolagus petenyii	2	16.70-14.30	15.50	–	2
Hypolagus brachygnathus	2	–	15.70	–	3
Hypolagus schreuderae Teilhard de Chardin, 1940 5		16.50-15.50	15.90	0.42	1
Hypolagus gromovi Gureev, 1964	1	–	15.91	–	1
Hypolagus petenyii	1	–	16.57	–	2
Hypolagus gromovi	7	18.50-15.10	17.07	–	3
Nuralagus rex Quintana, Köhler & Moyà-Solà, 2011 6		18.40-15.58	17.17	1.10	0

see Table 5 ; IPS-61604, distal epiphysis fragment of left humerus, see Fig. 5 ) The head of the humerus shows, from a lateral view, a very rounded outline. The lateral and medial faces of the proximal epiphysis are largely worn. The crests of the trochlea show a slightly sharp outline ( Fig. 5 ) and are quite separated. Remarks. The trochlea of the distal epiphysis is relatively wide ( Fig. 6B ) and the crests show a light acute outline in comparison to the other species included in the genus Hypolagus (Dawson 1958: fig. 30C; Fladerer 1984; Fladerer & Fiore 2003: pl. 2, fig. 2; Fostowicz-Frelik 2007b: figs 24-30). We exclude the possibility that the particular morphology of the IPS-61604 distal epiphysis is caused by abrasion due to taphonomic processes. In leporids, the development and separation of the crests and pits on the elbow articulation are likely related to the speed attained during running and leaping. Species better adapted to high speeds are those with more acute crests, whereas the non-running species have lower crests and the distal epiphysis is wider transversally, as it happens in N. rex (Quintana 2005: fig. 56) or, to a lesser extent, in Pentalagus furnessi (Stone, 1900) . Radius (IPS-61605, left proximal epiphysis) The fovea is shallow and the surface portion of the articulation situated on the lateral side is bended 42° in relation to the diaphysis. FIG. 5.— Distal epyphysis of the left humerus of: A , H.balearicus Quintana,Bover,Alcover,Agustí & Bailon,2010 (IPS-61604); B , O.cunicu- lus (Linnaeus, 1758). Dorsal views.Arrows shows the different development of the crests of the trochlea in both cases. Scale bar: 5 mm. Remarks. The craniocaudal diameter of the proximal radius from Eivissa is larger than that of its Mallorcan homologue, and the lateral margin is substantially lower ( Quintana et al. 2011 : fig. 8) ( Table 6 ). On H. balearicus the fovea is less concave than H. beremendensis (Petényi, 1864) (Fladerer 1984: abb. 5, figs 1, 2) and Hypolagus petenyii Čermák & Fladerer in Čermák, 2009 (Fostowicz-Frelik 2007a: figs 32, 34). The poor depth of the fovea is related to the low sharp outline of the lateral crest of the distal humeral epiphysis. Ulna (IPS-41733, right ulna without distal epiphysis, see Fig. 7 ; IPS-61606, left proximal epiphysis) From an anterior view, the anconeal process shows a well-rounded outline. The diaphysis is wide, both transversally and anteroposteriorly. ( Fig. 8 ; Table 7 ). Remarks. The rounded outline of the anconeal process suggests that the trochlea on the distal epiphysis of the humerus forms an arch with an opened outline, even more than in N. rex (Quintana 2005: fig.56a). Both, this trait and the morphology of the proximal radius in H. balearicus from Mallorca ( Quintana et al. 2010 : fig. 8), suggest that the crests and the elbow articulation pits in H. balearicus have a low acute contour. The ulna proximal epiphysis of H. balearicus shows an aspect considerably more robust than H. beremendensis (Fladerer 1984: abb. 6, fig. 1). In lateral view, the trochlear incisure of H. balearicus forms a similar arch than N. rex (Quintana 2005: fig. 72) and slight more open than H. beremendensis . Second metacarpal (IPS-61607, right proximal epiphysis, see Fig. 9B and Table 8 ; IPS-61608, right proximal epiphysis) From cranial view, the epiphysis shows a quadrangular outline. The trapezoid fossa forms an arch slightly open in mediolateral direction. The lateral crest (dorsal view) forms an angle of 75°. The medial crest is proportionally lower and rounded. The capitatum facet is bended more or less 40° in relation to the longitudinal axis of the diaphysis. From a lateral view, this facet shows a V-form outline, rather open and symmetric. The crest, which separates the facets for the capitatum and the third metacarpal, as well as the pit for the third meta- carpal form a gentle arch. On the first metacarpal facet, the ventral extreme is missed. It presents an elongated surface in dorsoventral direction, slightly irregular and concave in anteroposterior direction. FIG. 6.— Allometric representation of the humeral length ( A ) and transversal diameter of the humerus distal epiphysis ( B ) of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 in relation to other extant and fossil leporids. The allometric relationships are defined by the equations: A , log body mass = 0.3916 log humerus length – 0.4552 (r 2 = 0.8317); B , log body mass = 0.3748 log transversal diameter of humerus distal epiphysis – 0.2506 (r2 = 0.9388). Symbols: + , Hypolagus balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 ; ● , Pentalagus furnessi (Stone, 1900) ; �, Nuralagus rex Quintana, Köhler & Moyà-Solà, 2011 ; �, Pronolagus randensis Jameson, 1907 ; �, Pronolagus crassicaudatus (I. Geoffroy, 1832) ; Δ, Pronolagus rupestris (A. Smith, 1834) ; × , Sylvilagus floridanus (J. A. Allen, 1890) ; �, Sylvilagus nuttallii (Bachman, 1837) ; ◆ , Sylvilagus audubonii (Baird, 1858) ; ◯, Oryctolagus cuniculus (Linnaeus, 1758) ; �, Bunolagus monticularis (Thomas,1903) ; �, Lepus capensis Linnaeus,1758 ; Oi, Lepus granatensis Rosenhauer,1856 ; ◇, Lepus californicus Gray, 1837 ; � , Lepus saxatilis F. Cuvier, 1823 . Remarks. The proximal epiphysis of the second metacarpal of H. balearicus differs from O. cuniculus and Lepus granatensis Rosenhauer,1856 by a trapezoid fossa that is more open and wider in mediolateral direction and proportionally shorter in dorsoventral direction.The lateral crest is wider and less acute in H.balearicus .Cranial view, the proximal epiphysis of H. balearicus shows a quadrangular outline, while in N. rex and H. beremendensis is more elongated in dorsoventral direction (Quintana 2005: fig. 84; Fladerer 1984: abb. 19e). Femur (IPS-26589, left proximal epiphysis, see Fig. 9C ; IPS-41730, left proximal left epiphysis; IPS-41729, right diaphysis from a juvenile individual) From a dorsal view, the transversal section of the cranial face of the greater trochanter shows a rounded outline. The lesser trochanter is little elevated in mediolateral direction and in relation to the femoral neck. The dorsal margin of the femoral neck is short, so that the femoral head and the greater trochanter are close to each other. On the cranial face, the margin that separates the femoral head from the neck shows a low sharpened outline. The transversal section of the diaphysis has a circular outline. FIG. 7. — Proximal epiphysis of the right ulna of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 (IPS-41733) in cranial ( A ) and medial ( C ) views and of O. cuniculus (Linnaeus, 1758) in cranial ( B ) and medial ( D ) views. Abbreviations: a , humerus facet; b , radius facet. Arrows show the different development of the humerus facet in the medial surface. Scale bar: 5 mm. Remarks. The lateral margin of the femoral head of H. balearicus is proportionally closer to the greater trochanter than in O. cuniculus and H. petenyii (Fostowicz-Frelik 2007b: fig. 4). From a cranial view, the femoral neck length is proportionally shorter than in O. cuniculus but longer than H. petenyii . The minor trochanter is proportionally less developed in H. balearicus . The anteroposterior diameter of femoral head ( Table 9 ) is intermediate between Pronolagus rupestris (A. Smith, 1834) and H. petenyii . Tibia (IPS-61609, right distal epiphysis; IPS-61658, left distal epiphysis; IPS-61659, right distal epiphysis, see Fig. 9A ) The facet where the lateral margin of the astragalus is articulated shows a U-shaped outline. A groove, separating the lateral and medial face from this facet, is not observed. The cranial half of the calcaneus facet is wider than the caudal half and shows, in craniocaudal direction, a slightly concave outline. The area that separates the calcaneus and astaragalus facets shows an elliptic outline, with the principal axis pointing in craniocaudal direction. Remarks. The lateral fossa that articulates with the astragalus shows a mediolateral outline similar to that of L. granatensis and slightly less acute and more open than the one of O. cuniculus . However, the facet for articulation with calcaneus of H. balearicus shows a concavity (in craniocaudal direction) similar to O. cuniculus and clearly smaller than that in L. granatensis . The transversal diameter of H. balearicus tibia is slightly larger than that of O. cuniculus but smaller than that of Bunolagus monticularis (Thomas, 1903) ( Table 10 ). TABLE 5. — Length and transversal diameter (in mm) of the humerus diaphysis of H. balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 in relation to other leporids.

Length
Taxon	n	Max.-min.	Mean	SD
Sylvilagus audubonii (Baird, 1858)	17	54.24-42.35	47.56	3.06
Sylvilagus nuttallii (Bachman, 1837)	2	50.92-49.92	50.42	0.70
Sylvilagus brasiliensis (Linnaeus, 1758)	2	52.97-48.67	51.36	2.34
Oryctolagus cuniculus (Linnaeus, 1758)	14	59.09-50.59	54.97	2.78
Sylvilagus floridanus (J. A. Allen, 1890)	6-5	62.44-48.67	56.95	5.18
Nesolagus netcheri (Schlegel, 1880)	1	–	57.17	–
Poelagus marjorita (St. Leger, 1932)	1	–	59.55	–
Caprolagus hispidus (Pearson, 1839)	1	–	59.72	–
Hypolagus balearicus	1	–	60.12	–
Pronolagus rupestris (A. Smith, 1834)	5-4	66.12-59.90	63.27	3.06
Bunolagus monticularis (Thomas, 1903)	2	65.40-61.77	63.58	2.57
Pentalagus furnessi (Stone, 1900)	3	65.11-62.77	64.26	1.30
Pronolagus randensis Jameson, 1907	2	69.52-67.38	68.45	1.50
Pronolagus crassicaudatus (I. Geoffroy, 1832)	3	73.76-65.88	70.34	4.04
Lepus capensis Linnaeus, 1758	4	82.93-71.92	76.07	5.05
Lepus californicus Gray, 1837	6	78.70-74.47	76.41	1.49
Lepus granatensis Rosenhauer, 1856	3	78.96-75.10	77.03	2.72
Lepus saxatilis F. Cuvier, 1823	6	83.79-69.86	78.02	5.58
Lepus crawshayi De Winton, 1899	3	82.71-77.71	80.36	2.51
Lepus castroviejoi Palacios, 1976	2	88.81-83.06	85.93	4.06
Nuralagus rex Quintana, Köhler & Moyà-Solà, 2011 2-20		102.53-93.34	97.93	6.49
Shaft width
Taxon	Max.-min.	Mean	SD
Sylvilagus audubonii	3.57-2.43	3.14	0.35
Sylvilagus brasiliensis	3.33-3.26	3.29	0.04
Sylvilagus nuttallii	3.63-2.99	3.31	0.44
Sylvilagus floridanus	4.06-3.38	3.80	0.26
Oryctolagus cuniculus	4.43-3.44	3.90	0.30
Nesolagus netcheri	–	4.21	–
Bunolagus monticularis	4.64-4.08	4.36	0.39
Lepus californicus	4.91-4.23	4.56	0.27
Hypolagus balearicus	–	4.61	–
Poelagus marjorita	–	4.70	–
Lepus granatensis	5.95-4.28	4.88	0.93
Pentalagus furnessi	5.06-4.89	4.95	0.09
Caprolagus hispidus	–	5.00	–
Pronolagus rupestris	6.49-4.24	5.01	1.01
Lepus capensis	5.77-4.28	5.06	0.64
Lepus castroviejoi	5.16-5.00	5.08	0.10
Pronolagus randensis	5.58-4.93	5.25	0.45
Lepus crawshayi	5.50-4.84	5.25	0.35
Lepus saxatilis	6.42-4.46	5.30	0.78
Pronolagus crassicaudatus	6.18-4.87	5.48	0.65
Nuralagus rex	9.45-6.22	8.35	0.77

Navicular (IPS-61660, right incomplete bone, see Fig. 9D ) The astragalus pit shows a subquadrangular outline and a little marked concavity.On the plantar process, the ventral surface is slightly convex without any groove. Remarks. Due to its special traits, the recovered navicular of H. balearicus is interpreted as belonging to a juvenil individual. The astragalus fossa is notably more opened than in H. petenyii (Fostowicz-Frelik 2007: fig. 13), O. cuniculus and L. granatensis . The size of the navicular of H. balearicus is smaller in comparison to P.furnessi , Sylvilagus floridanus (J. A. Allen, 1890) or Lepus europaeus Pallas, 1778 (Fostowicz-Frelik 2007: pl. 3, p. 474). FIG. 8. — Allometric representation of the anteroposterior ( A ) and transversal diameter ( B ) of the ulna diaphysis of H. balearicus Quin- tana, Bover, Alcover, Agustí & Bailon, 2010 in relation to other extant and fossil leporids. The allometric relationships are defined by the equations: A , log body mass = 0.4062 log anteroposterior diameter of the ulna diaphysis – 0.7057 (r2 = 0.9628) (1: all the leporids except for the species included in the Lepus genus) and log body mass = 0.2987 log anteroposterior diameter of the ulna diaphysis – 0.4448 (r 2 = 0.4925) (2: for the species included in the Lepus genus); B , log body mass = 0.4064 log transversal diameter of ulna diaphysis – 0.7062 (r2 = 0.9633) (1: for all the leporids except the species included in the Lepus genus) and log body mass = 0.2987 log transversal diameter of ulna diaphysis – 0.4445 (r 2 = 0.4911) (2: for the species included in the Lepus genus). Symbols: + , Hypolagus balearicus Quintana, Bover, Alcover, Agustí & Bailon, 2010 ; ● , Pentalagus furnessi (Stone,1900) ; �, Nuralagus rex Quintana, Köhler & Moyà-Solà, 2011 ; �, Pronolagus randensis Jameson, 1907 ; �, Pronolagus crassicaudatus (I. Geoffroy, 1832) ; Δ, Pronolagus rupestris (A. Smith, 1834) ; × , Sylvilagus floridanus (J. A. Allen, 1890) ; �, Sylvilagus nuttallii (Bachman, 1837) ; ◆ , Sylvilagus audubonii (Baird, 1858) ; ◯, Oryctolagus cuniculus (Linnaeus, 1758) ; �, Bunolagus monticularis (Thomas, 1903) ; �, Lepus capensis Linnaeus, 1758 ; Oi, Lepus granatensis Rosenhauer, 1856 ; ◇, Lepus californicus Gray, 1837 ; � , Lepus saxatilis F. Cuvier, 1823 . Calcaneus (IPS-41732, right incomplete bone, see Fig. 10) The proximal facet of the astragalus shows a very acute anterior extreme and a concave surface, while the distal facet presents an elliptic outline (with the major axis slightly oblique in relation to the calcaneus length) and a slightly convex surface. The boundary between both facets shows a gentle outline. From medial view, the posterior half of the facet for the tibia shows a circular outline. The cuboid facet shows a piriform outline with a rather enlarged and slightly concave surface. TABLE 6. — Anteroposterior diameter (in mm) of the proximal radius epiphysis of H. balearicus Quintana,Bover,Alcover,Agustí & Bailon, 2010 compared with other leporids. Data sources of H. petenyii Čermák & Fladerer in Čermák, 2009 and H. brachygnathus (Petényi, 1864) : Fostowicz-Frelik (2007a, b).

Taxon	n	Max.-min.	Mean	SD
Sylvilagus nuttallii (Bachman, 1837)	2	2.82-2.77	2.79	0.03
Sylvilagus audubonii (Baird, 1858)	19	3.27-2.56	2.84	0.19
Sylvilagus brasiliensis (Linnaeus, 1758)	2	3.24-2.99	3.12	0.17
Hypolagus balearicus (Mallorca)	1	–	3.39	–
Sylvilagus floridanus (J. A. Allen, 1890)	6	3.73-3.15	3.43	0.24
Nesolagus netscheri (Schlegel, 1880)	1	–	3.49	–
Pronolagus rupestris (A. Smith, 1834)	2	3.54-3.48	3.51	0.03
Oryctolagus cuniculus (Linnaeus, 1758)	15	4.01-3.31	3.63	0.21
Hypolagus balearicus (Eivissa)	1	–	3.70	–
Bunolagus monticularis (Thomas, 1903)	2	3.88-3.69	3.79	0.13
Hypolagus petenyii	1	–	3.80	–
Hypolagus petenyii	11	–	3.80	0.30
Hypolagus petenyii	41	–	3.90	0.30
Hypolagus petenyii	3	–	3.90	–
Hypolagus petenyii	32	–	3.90	0.20
Poelagus marjorita (St. Leger, 1932)	1	–	4.07	–
Hypolagus petenyii	10	–	4.20	0.20
Pronolagus randensis Jameson, 1907	1	–	4.30	–
Pronolagus crassicaudatus (I. Geoffroy, 1832)	3	4.68-4.34	4.51	0.16
Caprolagus hispidus (Pearson, 1839)	1	–	4.60	–
Hypolagus brachygnathus	24	–	4.70	0.40
Lepus californicus Gray, 1837	7	5.17-4.67	4.80	0.17
Lepus capensis Linnaeus, 1758	4	5.39-4.53	4.89	0.36
Lepus saxatilis F. Cuvier, 1823	6	5.56-4.40	5.01	0.39
Lepus granatensis Rosenhauer, 1856	3	5.17-4.83	5.02	0.17
Pentalagus furnessi (Stone, 1900)	3	5.23-4.90	5.10	0.17
Lepus castroviejoi Palacios, 1976	2	5.38-4.98	5.18	0.28
Lepus crawshayi De Winton, 1899	3	5.29-5.21	5.26	0.04
Nuralagus rex Quintana, Köhler & Moyà-Solà, 2011	26	8.88-7.30	8.27	0.48

Remarks. The caudal half of calcaneus is proportionally robuster in H. balearicus than in O. cuniculus and L. granatensis because the caudal side of the cuboid facet is less pronounced. The lateroproximal astragalus facet is concave in H. balearicus , while it shows a marked convexity in O. cuniculus and L. granatensis . The form of the lateral outline of the tibial facet of H. balearicus shows an intermediate curvature, different from those in L. granatensis (clearly circular) and O. cuniculus (eliptico-oval).The mediolateral diameter of calcaneus of H. balearicus is larger than in O. cuniculus but smaller than in B. monticularis ( Table 11 ).