Trischizolagus Radulesco and Samson, 1967

Kalaitzi, Christina N. & Kostopoulos, Dimitris S., 2025, Craniodental anatomv of Late Ruscinian Trischizolagus (Leporidae: Lagomorpha) from Megalo Emvolon (Tessaloniki, Greece), Zoological Journal of the Linnean Society 204 (2) : -

Genus Trischizolagus Radulesco and Samson, 1967

Trischizolagus dumitrescuae Radulesco and Samson, 1967 Type species: Trischizolagus dumitrescuae Radulesco and Samson 1967: 547 ; bv original designation.

Holotype: Right mandibular ramus with p3-m1, I.S. 6001, Malusteni, Romania.

Original diagnosis: In Radulesco and Samson (1967: 547).

Studied material: Cranium; MVL-46, MVL-47, MVL-48, MVL-49, MVL-50, MVL-51, MVL-52, MVL-58, MVL-59, MVL-62, MVL-73a. Mandible; MVL-55 (dex i1-p3), MVL-63 (sin i1-m3), MVL-64 (sin i1-m2), MVL-65 (dex p3-m2), MVL-66 (dex i1-m3), MVL-67 (dex p3-m2), MVL-68 (sin p3-m3), MVL-69 (dex i1-m3), MVL-70 (dex p3-m3), MVL-71 (dex p3-m3), MVL-72 (sin i1-m3) and MVL-73b (dex i1-m3 and sin i1-m2). Upper dentition/teeth; MVL-46 (dex I1-M3 and sin I1-M3), MVL-47 (dex P2-M3 and sin P2-M3), MVL-48 (dex I1-I2, P3-M3 and sin I1-M3), MVL-49 (dex I1-I2, P3-M3 and sin I1-M3), MVL-50 (dex P2-M2 and P2-M3), MVL-51 (sin P2-M3), MVL-52 (dex P2-M3 and sin P2-M3), MVL-53 (dex P3-M2), MVL-54 (dex I1-I2 and sin I1-I2), MVL-56 (sin P3-M2), MVL-57 (dex P3-M2), MVL-73a (dex I1-M3 and sin I1-I2, P3), MVL-74 (dex I1-I2), MVL-76 (I1), MVL-80 (I2), MVL-81 (I2), MVL-85 (I1), MVL-153 (I1). Lower dentition/ teeth; MVL-55 (dex i1-p3), MVL-63 (sin i1-m3), MVL-64 (sin i1-m2), MVL-65 (dex p3-m2), MVL-66 (dex i1-m3), MVL-67 (dex p3-m2), MVL-68 (sin p3-m3), MVL-69 (dex i1-m3), MVL-70 (dex p3-m3), MVL-71 (dex p3-m3), MVL-72 (sin i1-m3) and MVL-73b (dex i1-m3 and sin i1-m2), MVL-82 (i1), MVL-83 (lower molariform), MVL-84 (lower molariform).

Description Seven partlv preserved (MVL-50, MVL-51, MVL-52, MVL-58, MVL-

59, MVL-62, and MVL-73a) ( Fig. 2E, F, I, J) and four fairlv complete

(MVL-46, MVL-47, MVL-48, and MVL-49) ( Fig. 3A–D; Supporting

Information, Models S 1, S2) crania are available along with several maxillarv parts ( NISP: 26), altogether indicating a MNI of 13. Except for the damaged posterior parts of the mandibular ramus and coronoid process, most mandibles are well-preserved. Seven specimens (MVL-55, MVL-63, MVL-64, MVL-66, MVL-69, MVL-72, and MVL-73b) maintain the bodv (corpus), the diastema, and most of the teeth ( Fig. 4A–F; Supporting Information, Models S 3, S4), whereas four specimens are more damaged and lack either the diastema or the dentition. Onlv in MVL-68, some areas of the masseteric fossa are recovered ( Fig. 4G). MVL-73b is the onlv specimen with the two hemimandibles intact. A total of 16 mandibles have been preserved, representing at least eight individuals. Cranial measurements are provided in Supporting Information, Table S1 .

Skull Nasals: Te complete nasal bones can be observed onlv in MVL- 47 in excellent condition ( Fig. 2D); the imprint of the nasals is preserved in the majoritv of the rest of the specimens, while the posterior portions are preserved in MVL-50 and in a bad condition in MVL-52. Te nasals are broadest posteriorlv to their narrowest point at their straight suture with the frontal bones and taper anteriorlv at the anterior nasal aperture. Te nasals form the upper part of the muzzle, which overall is short and wide. Te suture between the nasal and frontal bones forms a forward-pointing ‘V’ that extends slightlv bevond the zvgomatic shoulders and reaches approximatelv the level of the P4–M1 limit. In MVL-47, the dorsal sides of the nasals are somewhat convex over most of their anteroposterior length, except near the base of the frontal process, where thev flaten. A thin and verv prominent posterodorsal process of the premaxilla contacts the nasal bones and separates them from the maxilla ( Fig. 2D). A field of neurovascular foramina is located at the lateral border of the dorsal surface of each nasal, arranged along the premaxilla’s nasal process. Apart from MVL-47, similar fenestrations are visible in the preserved nasals of MVL-46 and MVL-50 ( Fig. 3B).

Premaxilla: Te paired premaxillae are relativelv long and bear both pairs of upper incisors. Tev create the anterolateral portions of the rostrum and contribute to the anterior part of the palate. In MVL-46–MVL-49, and MVL-73a, both premaxillae are almost fullv preserved. Te premaxillae of the remaining specimens have been severelv damaged. Te premaxilla can be split into two parts, the corpus (bodv) and three processes: a nasal process, a palatine process, and a maxillarv process. Both pairs of incisor alveoli are situated on the premaxillarv corpus. Te alveolus for the anterior upper incisor (I1) is proportionallv larger and located more anteriorlv and dorsallv than the alveolus for the posterior upper incisor (I2). Troughout the whole anteroposterior length of the premaxillarv corpus, both alveoli are posteriorlv extending and dorsallv curving. Dorsallv located on the premaxillarv corpus are multiple small neurovascular foramina present on its lateral surface. Tese foramina can be seen as a significant fenestration, albeit of a much smaller size than those described above for the nasals. Furthermore, in lateral view, at the premaxilla–maxilla suture of MVL-46, MVL-47, and MVL-73a, a significantlv larger, narrower, and longer fenestration appears. In ventral view, the length of the premaxilla occupies approximatelv half of the diastema. Te two premaxillae are robust, nonparallel, and form an angle of approximatelv 35 o with the first incisor roots at their apex.

In dorsal view, the nasal process of the premaxilla extends posterodorsallv from the corpus. It possesses a rather sharp ventral edge, and it is anteroposteriorlv elongated, dorsallv curved, and sub-triangular in shape. Te nasal process terminates anterior to the apex of the frontal process of the nasals, as seen in the available specimens. Troughout its entire anteroposterior length, the medial surface of the nasal process of the premaxilla is in contact with the lateral process of the premaxilla. Te maxillarv process of the frontal, which divides the premaxilla from the maxilla in dorsal view, is in contact with the ventrolateral side of the nasal process. In ventral view, the palatine process of the premaxilla is rarelv preserved. It can onlv be seen in MVL-46, MVL-47, and MVL-73a, extending posteriorlv from the anteromedial surface of the premaxillarv corpus. It is slender mediolaterallv and elongated anteroposteriorlv. Te anterior roof of the palatine process is located approximatelv 2 mm behind the alveoli of I 2 in occlusal view. Te posterior area has not been preserved ( Fig. 2C).

Maxilla: In most of the specimens, the maxilla is well preserved ( Fig. 3E, F, I). Τhe maxillarv corpus exhibits a roughlv trihedral shape. Te lateral wall of the maxillarv corpus is perforated bv numerous small openings. Tese fenestrations can be observed on the anteroventral and dorsal surfaces of the maxillarv corpus. All specimens show a large, sub-circular infraorbital foramen on the lateral side of the maxillarv corpus ( Fig. 2B).

Te anterior-ventral part of the maxillarv corpus has a narrow fissure that runs rostrocaudallv. Tis fissure is surrounded bv a series of long ridges and troughs that run from the front to the back. Tese ridges and vallevs fit tightlv with a series of similar structures on the back and front of the maxillarv process of the premaxilla. Te facial tuberositv is not pronounced. Te palatine process of the maxilla is preserved in all specimens except MVL-51, which lacks its right side. Te incisive foramen is long, extending posteriorlv to the limit of P2. Two rounded notches are formed at the posterior end of the incisive foramen, and thev extend posteriorlv to the mid-level of the paired P2, divided bv a not that sharp mesial palatal spine.

Palatine: Several parts of the palatine bone, forming the posterior portion of the hard palate, are preserved, enabling a detailed description of its anatomv. In MVL-46–MVL-48, the palatine is completelv preserved ( Figs 2C, 3A–F). It is onlv partiallv retained ( Fig. 3J) or abraded in the rest of the specimens.

In each hemipalatine, a lateral perpendicular lamina (portion) and a medial horizontal lamina can be distinguished. Te later forms almost the whole surface of the palatine and approximatelv the posterior part of each side of the hard palate. Te palate appears to be relativelv high, forming a deep concavitv between the maxillarv bones. In ventral view, the walls seem to have a slight slope, and the margins seem to narrow from top to botom. Te anterior margin is located at the level of the anterior part of P4, and the posterior margin bears a verv notable nasal spine, mediallv. Te sub-circular major palatine foramen is located near the maxillo-palatine suture, anterolaterallv. In four palates, the major palatine foramina open within the palatine while in other two thev are placed on the palatine–maxilla suture. Posteriorlv and posteromediallv to the incisive foramen, the palatine surface has several smaller additional foramina. An additional prominent foramen on the level of the anterior portions of M2 is seen in MVL-46 ( Fig. 3B). Te presphenoid and vomer are completelv damaged and hence cannot be available for description.

Zygomatic and squamosal: In several specimens (e.g. MVL-47– MVL-49) both of the zvgomatic bones are preserved; most of the rest retain onlv the right or the lef part intact. Anteriorlv, the maxilla’s zvgomatic process and the zvgomatic are extensivelv united to form a distinct ‘V-shaped’ structure that is positioned horizontallv on the bone ( Fig. 2B). Te zvgomatic is the broadest anteriorlv and mediolaterallv, and forms a basket-handle tvpe of arch morphologv. Its dorsoventral height graduallv increases posteriorlv until the middle of the bone and decreases abruptlv posteriorlv to its end. Te zvgomatic has a concavitv in both the lateral and medial sides, with the former creating a prominent zvgomatic fossa.

Te internal lateral surface of the middle cranial fossa is formed bv the squamosal, which resides in the lateral region of the braincase. It can be observed in all studied specimens, except MVL-73a. It consists of an anterolaterallv protruding zvgomatic process and the squama of the squamosal. Te cranial portion of the craniomandibular joint is tightlv connected to the posterior region of the zvgomatic process. Te zvgomatic process of the squamosal is not as broad as the zvgomatic arch and is positioned above the posterior margin of the zvgoma, providing an essentiallv trihedral morphologv with a conspicuous oblique line extending anteriorlv in lateral view. Lastlv, in most of the specimens, the squamosal and its sutures with the frontal and parietal are traceable.

Frontal: MVL-47–MVL-51 exhibit complete frontals; thev are partiallv preserved (MVL-52), seriouslv damaged (MVL-46), or even missing (MVL-73a) in the rest of the specimens. Te frontal bone can be separated into an orbital portion and the frontal squama, which are divided from each other bv the supraorbital rim (infraorbital margin). Te anterior part of the cranial roof and the posterior part of the dorsal wall of the nasal cavitv are formed bv the frontal squama. Te dorsal surface seems to be relativelv convex on most specimens, vet in MVL-49 and MVL-50 it is more flatened, probablv due to post-mortem deformation resulting in slight dorsoventral compaction. Piting is present on the dorsal surface of the frontal squama.

Te orbital portion of the frontal bone is concave mediallv and stronglv arched laterallv ( Fig. 2A, B). In dorsal view, the supraorbital process is verv prominent, thorn-like, and extends ventrallv to form part of the orbital wall. Te lacrimal, squamosal, parietal, and posterior surfaces of the frontal process of the maxilla are all abuted bv the orbital section of the frontal anteriorlv. Te lacrimal is positioned on the orbit’s anterior wall. Due to poor preservation, the lacrimal, as well as the orbits’ oblique dorsolateral view, cannot be described.

Parietal: Te posterior ceiling of the skull is formed bv the parietal pair, with the supraoccipital and interparietal adding a small basin and a thin strip in the posterior margin, respectivelv, and the squamosal contributing a narrow strip in the lateral and anterior–lateral edges. MVL-46, MVL-49, and MVL-51 have the paired parietal preserved in good condition ( Fig. 3A, C); MVL-47 and MVL-50 have onlv the lef parietal intact. Te piting continues and is visible in most specimens, especiallv at the lateral suture with the frontal and squamosal. However, it is less prominent in MVL-46, MVL-48, and MVL-50 ( Figs 2D, 3A, E).

Te braincase seems to be globular, although in some specimens a slight deformation of the cranium can be observed. It is noteworthv that the parietal width of MVL-48 is significantlv larger than that of the other specimens, due to taphonomv deformation ( Fig. 2A). Te posterior suture between the parietals is raised as a low sagital crest in MVL-46 and MVL-51 ( Fig. 3G, H). Te interparietal and supraoccipital regions are damaged in all specimens. Numerous small foramina on the external surfaces of the braincase bones can be observed in all specimens, especiallv in MVL-47, MVL-49, and MVL-51, where piting is verv prominent ( Figs 2D, 3A, C).

Basisphenoid, pterygoid, presphenoid, and alisphenoid: Te presphenoid is connected to the basal sphenoid and is located on the ventral side of the cranium. Te presphenoid bone forms the ventral and anterior boundaries of the optic foramen. Onlv in MVL-47 and MVL-48 is the presphenoid partiallv preserved ( Fig. 2C). It is verv thin and ventrodorsallv concave. Positioned anterior to the basioccipital and posterior to the presphenoid, the basisphenoid is situated near the base of the middle cranial fossa. In ventral view, the basisphenoid forms an isosceles triangular shape, as seen in MVL-47 and MVL-48 ( Fig. 2C). On the top medial side of the basisphenoid, the small, vet prominent pituitarv foramen can be observed in MVL-47 and MVL-48. Anterolaterallv to the basisphenoid, the paired ptervgoids are extending, onlv poorlv preserved in MVL-48. Te alisphenoids, firmlv united with the basisphenoid ventrallv, extend into the caudal orbital wall and continue to the caudal borders of the palatine bone, where thev form the ptervgoid process, which is damaged in all specimens.

Ectotympanic: Most cranial specimens preserve the ectotvmpanic, while MVL-58 and MVL-59 are isolated auditorv bullae ( Figs 2A, B, 3I, F). Te external acoustic meatus has the shape of a tube that leads within the auditorv bulla and is oriented posterolaterallv. Its external opening is large and ovalshaped. Te auditorv bullae are round, inflated, and have a smooth surface. Te front end is more rounded than its posterior counterpart, which is somewhat more pointed. Tev are angled slightlv toward the centre of the skull. Te petrosal, which occupies the posterodorsal region of the skull and is bordered anteriorlv bv the ectotvmpanic, is poorlv preserved in all specimens.

Occipital complex (basioccipital, exoccipital, and supraoccipital): At the back of the cranium, the occipital bone forms a bonv ring around the foramen magnum. Because of its general fragilitv, and likelv taphonomic agents, the occipital can onlv be seen to some extent in MVL-46, MVL-48, and MVL-51 ( Figs 2C, 3I). Te occipital comprises four portions: the basioccipital, exoccipitals, and supraoccipital. Te posterior section of the cranial base is occupied bv the basilar portion (basioccipital). It is onlv observable in MVL-48, which is in a good state, and partiallv in MVL-47, which is quite damaged. Anteroposteriorlv, it occurs as a pair of lobes, narrower anteriorlv and slightlv broader posteriorlv, approaching the foramen magnum. Te paired lateral sections (exoccipitals), mainlv seen in MVL-48, comprise the lateral borders of the foramen magnum and support the main portions of the occipital condvles. Te exoccipital creates a thin paracondvlar process lateral to the dorsal part of the occipital condvle. Tis process continues ventrolaterallv, forming a prominent ‘V-shaped’ morphologv with the occipital condvles. Te dorsolateral margins of the foramen magnum are formed bv the supraoccipital. Onlv in MVL-51 are fragments of the supraoccipital visible vet somewhat poorlv preserved; therefore, no anatomical description can be offered. When viewed ventrallv, in MVL-47, MVL-48, and MVL-51, the foramen magnum has a subcircular appearance that is somewhat compressed anteroposteriorlv. MVL-48 exhibits a somewhat larger foramen magnum, with wider-spaced occipital condvles.

Mandible: Te diastema is relativelv long and slender, somewhat longer than the alveolar length of p3–m3 ( Fig. 4A–F). Te alveolus for i1 is located anteriorlv on the mandibular bodv. Apart from the m3 alveolus, which is noticeablv smaller, the posterior dorsal side of the mandibular bodv includes alveoli for p3–p4 and m1–m3. Tese alveoli are approximatelv comparable in size. Te dorsal side of the mandibular bodv is somewhat concave and contributes to the ventral half of the diastema, located between the alveoli of the i1 and p3. Tere is a mental foramen located between the alveoli approximatelv at the posterior third of the anteroposterior length of the diastema, which is probablv homologous with the mental foramen in leporids located in a similar position ( Wible 2007). Te buccal surface of the bodv is richlv fenestrated and, to a lesser degree, the lingual one as well ( Fig. 4A–E). In addition, the lateral surface of the mandibular corpus at the retromolar fossa bears a prominent and round-shaped neurovascular foramen dorsallv. Te lower incisive root protrudes from the lingual side of the bodv and extends posteriorlv below the anterior border of p3. Lastlv, the ventral side of the mandibular bodv has a noticeable mvlohvoid line for the mvlohvoid muscle insertion.

Dentition I1 and I2: In total, 13 I1 (eight in anatomical position and five isolated) and 12 I2 (10 intact and two isolated) are preserved ( Table 1). Te occlusal outline of the upper incisors has an asvmmetrical quadrangular shape that extends anteriorlv in its medial part. Te mesial enamel is relativelv thin with no substantial variation. Te anterior notch is ‘V-shaped’ and shallow, with wide, open walls and is not filled with cement. It separates the tooth into two parts of approximatelv equal anterior prominence. Te second upper incisors are rounded and mediolaterallv elongated. Encircling the teeth, the enamel is thin.

P2: Twelve P 2 specimens are available ( Table 1; Fig. 3K, L), all of which are still preserved in the maxilla. Te occlusal outline of the teeth is generallv oval. Tev displav three flexus, of which the paraflexus is the deepest, while the hvpoflexus and mesoflexus are shallower or almost absent. When present, the hvpoflexus and mesoflexus are labiallv and mesiobuccallv situated, respectivelv. In all specimens the flexus is filled with cement. Te development of the hvpoflexus ranges from nonexistent (lef side of MVL-46) to usuallv weak, forming a shallow-narrow notch (MVL-46 right side, MVL-47, MVL-48, MVL-49, MVL-51, and MVL-52) to beter defined and more prominent, forming a less shallow and narrower notch (MVL-50 lef side, MVL-73a). In several specimens (MVL-46, 50, 73a) small differences in hvpoflexus development are observed between the right and lef P2. Te mesoflexus is usuallv shallow and forms a relativelv broad ‘V-shaped’ notch, weakest in MVL-49, deeper and wider in MVL-52 (right side) and MVL-47, and narrower in MVL-51, 73a.

Te hvpercone is advanced, achieving the same width development as the lagicone and postcone combined. Te later forms a 45 o angle with the distal hvperloph, whereas the hvpercone has a 25 o to 30 o gradient. Following Fladerer and Reiner (1996) and Čermák (2009), the lagicone is of the B morphotvpe, and the hvpercone is between the IV and V tvpes of enamel structures.

Upper molariforms: Te morphologv of the upper molariform teeth (P3–M3) exhibit a folded hvpoflexus crossing more than half of the tooth width and highlv crenulated in most of the specimens, with extensive cement linguallv ( Table 1; Fig. 3K, L). Enamel is ofen denser on the mesial part of the anteroloph and the lingual tips of the posteroloph. Te P3, P4, M1, and M2 are of comparable size, but the M3 is considerablv smaller. M3 lacks a hvpoflexus and is round-shaped. In addition, the separation between the talonid and trigonid is not easilv traceable. Te folded hvpoflexus of M2 is approximatelv half the width of the tooth crown. Te degree (number and depth) of crenulation decreases from P3 to M2, with P3 and P4 exhibiting more prominent crenulations. Te P3 and most of the P4 trigonids have a narrower width than the talonid. Te situation is reversed at M1 and M2, where the trigonid has a larger width than the talonid. In terms of enamel stages, MVL-49 has the most worn teeth, with nearlv no enamel remaining. MVL-46 and MVL-73a have less damaged enamel than MVL-49, although thev are much poorer than the remainder of the specimens. Te enamel in the studied material appears to be weaker in the labial sections of the dentition while staving stronger in the buccal parts. Notablv, the wear stage of the enamel differs significantlv between the lef and right maxillae in three specimens. In MVL-48, MVL-52, and not as prominentlv in MVL-50, the lef dentition is more worn than the right.

i1: In total, 10 lower incisors are available from MVL ( Table 2). Te i1 is quadrangular and markedlv prolonged mesiodistallv. Te anterior enamel wall is constantlv thick. In MVL-64, MVL-69, and MVL-72, the occlusal surface is longer mesiodistallv, but not in MVL-63, MVL-66, and MVL-73b, where the surface is more square-shaped. Te i1 does not extend to below the p3.

p3: Among the 12 p3 ( Table 2), onlv one is isolated and most are well-preserved. Te tooth shaf is prismatic with a rhombic occlusal outline. It is quadrangular and prolonged mesiodistallv. Te tooth can be divided into two main parts. Te first is the anterior loph, the trigonid, which is divided into four lobes (conids), and the second is the posterior loph, the talonid, which consists of one lobe prolonged labiallv. Te later is approximatelv one-third of the width of the trigonid. Te two lobes are connected bv a dentine isthmus that is overall quite wide and short. Te development of the anteroflexid (AR) shows variations among the specimens. It can be distinguished in three main morphologies: a shallow and narrow ‘V-shaped’ AR (MVL-55, MVL-64, MVL-67, MVL-71, and MVL-73b sin) ( Fig. 4J); a narrow ‘U-shaped’ AR, less shallow than the previous tvpe and quite wider (MVL-63, MVL-66, MVL-69, MVL-70, and MVL-73b dex) ( Fig. 4H, I); and a wide, deep ‘U-shaped’ AR (MVL-65) ( Fig. 4K). MVL-72 has a bilobal anteroconid with dual anteroflexids that are wide and short ( Fig. 4L). Te hvpoflexid ( PER) and the mesoflexid ( PIR) are the deepest flexids, dividing the tooth into the trigonid and talonid parts, buccallv and linguallv, respectivelv. In most of the specimens, the two flexids are of equal development. However, in MVL-69, MVL-72, and MVL-73b, it is clear that the PIR is not as deep as PER and shorter. Te PIR is nearlv half the length of PER in MVL-72 and quite shallow. In MVL-69 and MVL-73b, the PIR is approximatelv two-thirds of PER length. Te angle of the hvpoflexid shows variations in the studied material, exhibiting a slope of about 45 o towards the talonid. Te gradient is more prominent in MVL-73b and lower in MVL-55, MVL-66, MVL-69, and MVL-71. Te protoflexid ( AER) also exhibits a varietv of different developments in MVL. It can be distinguished in two main morphotvpes. Te first one shows a shallow and wide ‘V-shaped’ AER (shown in MVL-63, MVL-65, MVL-70, MVL-71, and MVL-73b dex) and the second a narrow and shallow ‘L-shaped’ AER (seen in MVL-55, MVL-66, MVL-67, MVL-69, MVL-72, and MVL-73b sin). Lastlv, the hvpoconid is relativelv massive and rectangular. Te buccal side of the hvpoconid shows a small, rounded notch with verv thin enamel. Te PR1/A1 or Alilepus patern (i.e. no mesofossetid/presence of anteroflexid) is the onlv one recorded (100%; N = 12). Following Fladerer and Reiner (1996) and Čermák (2009), the hvpoconid is predominantlv of the ‘c morphotvpe’ (MVL-63, MVL-65, MVL-66, MVL-69, and MVL-71), more rarelv of the ‘a morphotvpe’ (MVL-55) or ‘b morphotvpe’ (MVL-70 and MVL-72), whereas also an in-between stage of ‘morphotvpes b–c’ is found (MVL-66 and MVL-73b). Te hvpoflexid is of the ‘A morphotvpe’ in MVL-71, the ‘C morphotvpe’ in MVL-65, MVL-66, MVL-69, and MVL-73b, and the ‘D morphotvpe’ in MVL-55, MVL-70, and MVL-72. An in-between stage of the ‘C and D morphotvpe’ is shown in MVL-63.

Lower molariforms: Te two cvlindrical shafs united bv a small bridge at the lingual side characterize the morphologv of all teeth, which is tvpical of the great majoritv of leporid species ( Table 2; Fig. 4H). In contrast to the p3, the rest of the lower molariforms (p4, m1, m2, and m3) in Lagomorpha are rather consistent and do not displav anv remarkable traits. In comparison with the talonid, the trigonid is larger (both in length and width). Te mesiobuccal corner of the trigonid is small and smooth. Mesiolabiallv, the labial portion of the talonid is convex. Te isthmus joining the trigonid and talonid is lengthv and narrow. Te flexid between the trigonid and talonid is smooth, and the enamel on the labial portion of the trigonid’s distal edge is extremelv thick. Te p3, p4, and m1 are of comparable size; however, the m2 is considerablv smaller. In addition, the m3 is cvlindrical-shaped, and the talonid portion is round, as opposed to the cvlindrical shape of the remainder of the lower molariforms. No crenulations are noticeable. Regarding the overall tooth wear, the enamel is more damaged or even completelv absent on the lingual side of the molariform teeth, as in the upper dentition. Te most worn molariforms are those of MVL-65 and MVL-67 coupled with a less worn p3 than the remainder of the teeth.

Comparisons

Our comparison is focused on the lower third premolar (p3), which is considered to be one of the most diagnostic anatomical elements on leporid taxonomv. Te second upper premolar also plavs an important taxonomic role but less so than the p3 (e.g. Radulesco and Samson 1967, Erbajeva and Angermann 1983, Averianov and Tesakov 1997, López Martínez et al. 2007). Te cranial anatomv of leporids, especiallv fossil ones, has not been comprehensivelv documented. Cranial findings are uncommon in the fossil record, and when thev do occur, thev mostlv comprise of fragments of the skull (e.g. Dietrich 1942, Averianov and Tesakov 1997, Asher et al. 2005, Şen and Geraads 2023). Hence, we compare the cranium of the MVL taxon with extant leporid species, as well as with available fossil crania of related leporids.

Dental comparison: Te p3 of Hypolagus Dice, 1917 lacks an anteroflexid and a mesoflexid (A0/PR0 tvpe), thus differing from the studied material (Čermák 2009, Čermák and Wagner 2013). Pliopentalagus Gureev and Konkova, 1964 has a three-folded trigonid p3 ( Alilepus patern) like the MVL sample, but the anterior enamel of its talonid is highlv crenulated ( Tomida and Jin 2005) in contrast to the much simpler enamel of our sample. In addition, the enamel of the mesial edge of the talonid on the m2 is also crenulated in Pliopentalagus in contrast to the material from MVL ( Tomida and Jin 2005). While Alilepus possesses a mesoflexid or a mesofossetid on p3 (A0/PR1–2 tvpe) (Čermák and Wagner 2013, Čermák et al. 2015), it lacks an anteroflexid, which contrasts with the MVL morphologv. Different from MVL, the p3 of Serengetilagus is rounded-shaped (or crescentlike), lacks anterior and posterior lingual flexids ( AIR, PIR, respectivelv), the lingual anteroconid is weaker than the buccal one and the anteroflexid is weak to absent. In addition to that, it is reported that the upper molariform teeth from both African species of Serengetilagus show a well-crenulated enamel along the distal wall of the hvpoflexus ( López-Martínez et al. 2007). Te morphologv of the folded hvpoflexus in MVL is much simpler and occurs primarlv on the mesial side. Lepus Linnaeus, 1758 and Oryctolagus Lilljeborg, 1874 , have the leporine tvpe of p3 but other than the MVL taxon thev displav a deep PER and no/ weaker PIR, together with ofen stronglv crenulated enamel (A1/PR3 tvpe) ( Hibbard 1963, López-Martínez 1980, Callou 1997).

Te dental features, and especiallv the p3 morphologv of the studied leporid material from MVL, fit perfectlv those of the genus Trischizolagus with which it shares the following diagnostic features: (i) the presence of a three-folded trigonid in p3 ( Alilepus patern); (ii) the rhombic outline of p3 with a broad lingual anteroconid and a well-developed AR; and (iii) the simple and uncrenulated enamel patern of the lower and upper check teeth (Averianov and Tesakov 1997, Čermák and Wagner 2013).

Čermák and Wagner (2013) provided a comprehensive review of Trischizolagus and recognized six species: T. crusafonti ( Janvier and Montenat 1971) ; T. dumitrescuae ; T. gambariani ( Melik-Adamvan 1986) ; T. maritsae de Bruijn et al., 1970 ; T. mirificus Qiu and Storch, 2000 ; T. nihewanensis (Cai, 1989) ; and T. raynali ( Geraads 1994) . Şen et al. (2024) confirmed with new data the debatable generic atribution of the later species (e.g. Şen and Erbajeva 1995, Averianov and Tesakov 1997, López-Martínez et al. 2007, Čermák and Wagner 2013), while Şen and Geraads (2023) added recentlv one more species, T. meridionalis Şen and Geraads, 2023 from Morocco.

Trischizolagus crusafonti was originallv described from the latest Miocene (MN 13) site of La Alberca in the Fortuna Basin, southern Spain ( Janvier and Montenat 1971). Şen (2020) also referred to this species some specimens from the Earlv Pliocene of Dorkovo in Bulgaria. Te overall teeth dimensions of the MVL teeth are significantlv larger than those from La Alberca and Dorkovo ( Fig. 5). Regarding its morphologv, the p3 of T. crusafonti is atributed to the Hypolagus patern (PR0), in contrast to the Alilepus (PR1) patern shown in MVL. Te T. crusafonti p3 displavs a deep PER that exceeds half the width of the occlusal surface, and it is curved backward in some specimens; in MVL, PER is not so deep. In the La Alberca specimens, the mesofossetid is missing, while in one Dorkovo specimen it is present ( Şen 2020). From the illustrations in Şen (2020), T. crusafonti follows a mainlv A1/PR0 patern in p3, while one specimen in Dorkovo displavs a PR2 patern in contrast to the A1/ PR1 patern of MVL. Te P2 of T. crusafonti displavs three flexi, consistentlv with MVL. Like in the MVL specimens, the level of enamel crenulation observed from the third premolar to the second molar is reduced in T. crusafonti .

Te dimensions of T. gambariani from the Εarlv Pliocene (MN14) of Nurnus in Armenia ( Melik-Adamvan 1986) and Tepe Alagöz in Turkev ( Čermák et al. 2019), indicate a smaller size compared to the MVL taxon ( Fig. 5). Te lower molariforms are also smaller. In comparison to the leporid from MVL, the p3 mesoflexid of T. gambariani exhibits the Nekrolagus (PR2) pattern (>90%), and hence the p3 is primarilv limited to the A1/ PR2 patern ( Čermák et al. 2019), in sharp contrast to MVL. Te P2 of T. gambariani displavs no significant morphological differences and presents the same variabilitv as that seen in MVL. Nevertheless, the P2 size range of T. gambariani is much smaller than that of the studied sample. Apart from the dimension, no noteworthv distinctions were detected between the lower and upper check teeth of the two taxa.

Trischizolagus maritsae from the Greek island of Rhodos represents one of the earliest documented species of Trischizolagus in eastern and south-eastern Europe, dated to the Mio-Pliocene transition ( De Bruijn et al. 1970, Vasileiadou and Svlvestrou 2022), and is the smallest species recorded so far in this genus, clearlv smaller than MVL ( Fig. 5). Te tvpe mandible is too worn for displaving the full p3 patern, but a paraflexid (AIR) is traced as in the rest of the Maritsa specimens. In the other two p3 from Maritsa, a mesoflexid (PIR) is well-defined. According to Čermák and Wagner (2013), the Hypolagus (PR0) p3 patern predominates in T. maritsae , in contrast to MVL. Koufos and Koliadimou (1993) assigned three upper molariforms from the Megalo Emvolon-1 localitv (MEV-1005) to Trischizolagus cf. maritsae . Te size of MEV-1005 falls within the known size range of T. maritsae ( Fig. 5) in distinction from MVL. Considering that no p3 has been found in MEV, the authors suggested that it is unclear whether MEV-1005 meets the criteria to be assigned to T. maritsae or is a smaller individual of T. dumitrescuae , the second species reported bv them in the site.

Trischizolagus mirificus was described from the Pliocene (MN14) localitv of Bilike in Inner Mongolia, China ( Qiu and Storch 2000). Te p3 of this species exhibits a discernible dissimilaritv from the MVL taxon, as it displavs a significantlv less complex, Hypolagus -like (PR0) morphologv, characterized bv less prominent folds on the trigonid. Te P2 of T. mirificus exhibits a simplified occlusal outline (mesoflexus and hvpoflexus nearlv undeveloped), in contrast to MVL. Trischizolagus mirificus is also much smaller compared to the MVL taxon ( Fig. 5) ( Qiu and Storch 2000).

Another species from China, T. nihewanensis , is from the lower part of the Daodi Formation (MN16) of Yangvuan and Yuixian ( Hebei Province) ( Tomida and Jin 2005). Te onlv available p3 (GMC V 2008 -1) shares the same Alilepus (PR1) patern with the MVL specimens, while exhibiting clear infolded walls of posterior tooth structures. MVL-72, as previouslv described, exhibits a bilobal anteroconid with dual anteroflexids that are wide and short, similar to the two folds in the anteroconid of T. nihewanensis . Te isthmus connecting the trigonid to the talonid is rather small in T. nihewanensis , while in the MVL specimens it is much wider. Tomida and Jin (2005) reported that the p3 of T. nihewanensis has the most complicated enamel patern among the species of the genus, in contrast to the much simpler and uncrenulated enamel in the MVL leporid. Te p3 of T. nihewanensis falls within the dimensional variabilitv of MVL sample ( Fig. 5), especiallv close to the length of MVL-73b and MVL-63, but it is generallv narrower. Te p4/m1 also shows weak crenulation on the thin enamel of the anterior edge of the talonid in T. nihewanensis , which is not observed in anv of the MVL specimens. Te remaining specimen of T. nihewanensis , a lef m2, exhibits no significant differences from the MVL ones and are comparable in size ( Tomida and Jin 2005).

Trischizolagus raynali from the Pleistocene localitv of Grote des Rhinos in Morocco ( Geraads 1994, Şen et al. 2024) differs from the MVL taxon in the predominance of the Nekrolagus (PR2) patern in p3, which displavs a mesofossetid (A1/PR2). Likewise, newlv discovered material from this species in Tomas Quarrv ( Morocco) and Earlv Pleistocene of Tighennif ( Algeria) predominantlv exhibit the PR2 patern, with onlv 6% of the specimens from Tighennif showing the PR1 ( Şen et al. 2024). In all cases, T. raynali is significantlv smaller in size, well outside the p3 size range observed at MVL ( Fig. 5).

Trischizolagus meridionalis from the Plio-Pleistocene localitv of Ahl al Oughlam, Morocco was recentlv described ( Şen and Geraads 2023). Te most notable difference between T. meridionalis and the material studied is its substantiallv smaller dimensions ( Fig. 5). Additionallv, nearlv half of T. meridionalis p3s have a mesofossetid (PR2; Şen and Geraads 2023), while a deep and narrow AR separates the anteroconid into two almost equal-sized conids, with the buccal one not protruding unlike MVL. Regarding the mandible, the specimens from Ahl al Oughlam exhibit the buccal face of the bodv to be perforated bv manv foramina, primarilv under the p3 and along the ventral side of the corpus below the diastema. Tis tvpe of fenestration is rather prominent and common, as observed from the available illustrations provided ( Şen and Geraads 2023). Onlv in MVL-65 and MVL-73b a fenestration of that kind can be observed, while in the rest of the available MVL specimens the fenestration is not so prominent. Te P2s of the MVL leporid are less compressed in contrast to the more mesiodistallv compressed P2 of T. meridionalis , causing the hvpoflexus and mesoflexus to be shallow but distinct. However, the development of the three flexi is variable in both T. meridionalis and the MVL taxon. Te size of the P2 is significantlv larger in MVL than in T. meridionalis . Te rest of the upper molariform teeth do not show anv major dissimilarities.

According to Averianov and Tesakov (1997) and Čermák and Wagner (2013), sixteen Earlv Pliocene (MN 14–15) localities in Bulgaria, Greece, Germanv, Hungarv, Moldova, Romania, and southern Ukraine include evidence of Trischizolagus dumitrescuae , while Wu and Flvnn (2017) also referred to Trischizolagus aff. dumitrescuae from northern China. Te Alilepus (PR1) patern is the prevailing one in all sites where T. dumitrescuae is recorded, with the Nekrolagus (PR2) patern following in frequencv (Čermák and Wagner 2013).

Te p3 on the holotvpe mandible of T. dumitrescuae (I.S. 6001) from Malusteni, Romania, is characterized bv an A1/Pa1/PR1 p3 morphologv, which is consistent with the MVL specimens ( Radulesco and Samson 1967, 1995, Averianov 1995, Čermák and Wagner 2013). Te anteroflexid (AR) of I.S. 6001 shows a comparable degree of development to that observed in the specimens from MVL, as evidenced bv the sketches presented bv Radulesco and Samson (1967) and Crespo et al. (2023). In both the tvpe specimen and MVL (especiallv in MVL-69, MVL-72, and MVL-73), the AR divides the anteroconid into two nearlv equal halves. Te AIR is relativelv narrow and shallow, whereas the AER is wider and deeper in both the MVL and I.S. 6001. Te PER and PIR of I.S. 6001 p3 are compatible with those from MVL. In addition, the trapezoidal shape of the talonid remains consistent in both the Romanian tvpe specimen and the majoritv of the MVL specimens, albeit some MVL toothrows displav reduced enamel on the buccal side of the hvpoconid and lack of the characteristic notch possiblv due to the wear stage of the enamel.

Additional specimens of T. dumitrescuae recovered from Malusteni exhibit a comparable size ( Fig. 5) and morphologv of p3 with both the holotvpe and the MVL sample. Te PR2 patern has been observed in a single specimen from Malusteni (I.S. 6008) in contrast to the more common PR1. Based on the measurements provided bv Crespo et al. (2023), the p3 size range of the species at this Romanian localitv overlaps with the size range recorded for the MVL sample. Regarding the mandible, the length of the diastema is onlv available for one specimen (I.S. 6008); it is measured at 19.5 mm ( Radulesco and Samson 1967), exceeding the measured range of 15.56 to 18.01 mm ( N = 8) in the MVL material. Te mandibular fenestration is in both the MVL specimens and those from Malusteni prominent on the buccal side of the mandibular corpus at the level of the premolars and in the lower region where the mental foramen is located.

Two p 3 specimens (I.S. 6006 and I.S. 6007) of T. dumitrescuae are reported from Berești ( Romania). I.S. 6007 is notablv smaller than the MVL specimens, while I.S. 6006 falls within the lower size range of MVL. According to the illustrations provided bv Radulesco and Samson (1967), the morphologv of these two specimens is similar to that of MVL. As noted in the revision of Malusteni and Berești bv Crespo et al. (2023), a significant number of specimens were lost, including the second upper premolar. No distinct size variations were provided for the upper premolars and molars, with onlv a size range for the upper molariforms (P4, M1, and M2) available ( Crespo et al. 2023). Nevertheless, the size range of the upper molariforms from MVL generallv aligns with those from both Berești and Malusteni.

Averianov and Tesakov (1997) described a rich material of Trischizolagus from Moldova and Ukraine, the vast majoritv of which was atributed to T. dumitrescuae . Unfortunatelv, the available information is poor. As in the MVL leporid, the East European sample shows the rhombic-rectangular p3 outline, which is accompanied bv a relativelv short and wide anteroconid in all cases. Te PR1 patern is the predominant, as reported bv Averianov and Tesakov (1997) and Čermák and Wagner (2013). Tese traits are consistent with the MVL leporid.

Čermák and Wagner (2013) documented two records of T. dumitrescuae from the Beremend 39 site in Hungarv (MN15b). Te first specimen comprises a lower mandible encompassing p3 to m2. It displavs the PR2 patern on p3, in contrast to the MVL specimens but it exhibits a bilobal AR that is similar to that observed in MVL-72. In terms of phvsical dimensions, the Hungarian specimen has a large p3, close to the length measurements of MVL-69 and MVL-70 but slightlv narrower. Te remaining molariforms fall within the size range of the MVL specimens, albeit in the higher part of the variation. Te dimensions of both the diastema and the alveolar region are significantlv larger in the Hungarian specimens ( 21.11 mm in Beremend 39) compared to those from MVL ( 15.56–18.01 mm), while the length of the alveoli region ranges from 15.13 to 16.78 mm in MVL versus 18.2 mm in the Hungarian specimen. Te second Hungarian specimen has been atributed to cf. Trischizolagus dumitrescuae and comprises a single fragment of a lef mandibular bodv bearing p3–p4. Te patern of p3 corresponds to that of Alilepus as in MVL. Te anteroconid exhibits a broad morphologv, defined bv an undulating enamel patern similar to that of MVL-65.

Te previouslv described specimens of T. dumitrescuae from the Megalo Emvolon-1 site (MEV) are also being compared with the newlv discovered ones of MVL. Te four available specimens, MEV-1001 (lower lef and right upper maxillae with P2–M3), MEV-1002 (lef mandibular fragment with p4–m2), MEV-1003 (lower lef mandibular fragment of p3–m3), and MEV-1004 (lower lef incisor), fullv match those described in the present studv on the P2 and p3 morphologv and overall size. Apart from the poor preservation, the PIR of MEV-1003 p3 seems to be linguallv closed while retaining the appearance of a fold. Although none of the MVL specimens have a closed mesoflexid, in MVL-70 and MVL-73b it is near to shuting. As in MVL-73b, the AIR of MEV-1003 p3 is quite broad and open. According to Fladerer and Reiner (1996) and Čermák (2009), the hvpoconid of MEV-1003 is either of an ‘e’ or ‘d morphotvpe’, and the hvpoflexid shows an ‘A’ or ‘C morphotvpe’. Although none of the MVL specimens show a similar hvpoconid to MEV-1003, its hvpoflexid is like that in MVL-65, MVL-66, MVL-69, MVL-71, and MVL-73b.

Cranial comparison: A cranial comparison with extant leporid taxa is provided in the Supporting Information, Appendix S1. Alilepus hibbardi White 1991 (IMNH 38695) is known for a complete skull recovered from the Late Miocene of North America ( White 1991). It exhibits cranial dimensions close to those of MVL. Nevertheless, the premaxilla is shorter, and the degree of fenestration observed in the maxilla and premaxilla is less advanced than in MVL. White’s (1991) illustrations indicate that the zvgomatic arches exhibit a similar level of inclination as those observed in MVL. Nevertheless, when viewed laterallv, the posterior end of the zvgomatic arches is situated at a higher position in A. hibbardi relative to that of MVL, resulting in comparativelv smaller eve sockets. Te anterior portion of the nasals is wider in A. hibbardi and the supraorbital process of the frontal bone shows a greater development being more rounded and laterallv extended, therebv leading to a posterior flexid that is wider and deeper in comparison to the thorn-like state seen in MVL. Te palate of Alilepus shares a similar relative length to that of MVL (index I4, Supporting Information, Fig. S1). On the other hand, compared to MVL, A. hibbardi has narrower incisive foramen (index I2) and a shorter upper diastema (index I6, Supporting Information, Fig.S1). On the mandible, the diastema is shorter in A. hibbardi (index I10, Supporting Information, Fig. S1) and more concave than in MVL ( White 1991).

Hypolagus balearicus Quintana et al., 2010 from the Earlv Pliocene localitv of Ses Fontanelles (Eivissa) ( Balearic Islands, Western Mediterranean Sea) (Cardona and Moncunill-Solé 2014), is one of the few Eurasian fossil species known bv its skull. Although poorlv preserved and lacking its dentition, the much smaller cranium of H. balearicus also differs from the MVL one in the narrower palate and choanae, and the more laterallv elongated root of the zvgomatic process of the maxilla (Cardona and Moncunill-Solé 2014).

According to the descriptions and illustrations bv Dietrich (1942), the muzzle region of Serengetilagus praecapensis Dietricht, 1941 cranium from the Middle Pliocene of Laetoli, Tanzania, appears to be comparable to that of MVL in dorsal view. Nevertheless, when viewed laterallv, the rostrum of S. praecapensis appears to occupv a significantlv greater surface than in MVL and its muzzle top area is more arched. In addition, the maxillarv fenestration in S. praecapensis seems to be more prominent than in MVL, but limited to the posterior part of the maxilla, once again in contrast to the MVL cranium in which the premaxilla shows prominent piting. Te supraorbital process of S. praecapensis shares the same development as in MVL. Te zvgoma of S. praecapensis is higher positioned compared to MVL and exhibits a more angular lower portion as it shows a noticeable change in slope halfwav along its length, resulting in a steeper angle towards the posterior end. Tis contrasts sharplv with the zvgoma of the MVL cranium, which maintains a consistent slope throughout its entire length, lacking anv mid-arch angular transition. Te incisive foramen of S. praecapensis is wider than that of MVL (index I2, Supporting Information, Fig. S1) and the palate is shorter (index I4, Supporting Information, Fig. S1). In addition, the upper diastema of S. praecapensis is longer than in MVL ( López-Martínez et al. 2007, Şen and Geraads 2023). It must be noted that the ratio of choanae breadth to palatal length for S. praecapensis has not been indicated bv Dietrich (1942), but according to the notes of López-Martínez et al. (2007) it would be larger than 1. Measurements provided from Şen and Geraads (2023) suggest a ratio about 1.3; it is close to 1 in MVL. Lastlv, the lower diastema of S. praecapensis is shorter than in MVL.

Few cranial remains of S. tchadensis López-Martínez et al., 2007 have been found from the Late Miocene deposits in the Toros Menalla region of Northern Chad ( López-Martínez et al. 2007). From the limited available measurements, S. tchadensis exhibits a longer palate (index I4, Supporting Information, Fig. S1) and a shorter upper diastema (index I6, Supporting Information, Fig. S1) than MVL. Te breadth of the incisive foramen is similar to that of MVL (index I2, Supporting Information, Fig. S1) ( Şen and Geraads 2023).

According to Averianov (1995), the remains of T. dumitrescuae crania are limited to two small fragments of the frontal and occipital bones from southern Moldova. Regretablv, onlv sketches are accessible, and thus, we base our comparison onlv on the descriptions. Te median portion of the preserved right frontal does not differ from the condition seen in L. europaeus , similarlv to MVL. Averianov (1995) highlights that the foramen magnum displavs a resemblance to that of L. europaeus , wherein it is positioned more superiorlv. Tis description appears to be inconsistent with that of the MVL leporid where the foramen magnum is preserved. Te placement of the foramen magnum in these MVL crania is relativelv more posterior and can onlv be fullv observed from an occipital viewpoint. Averianov (1995) concluded that the auditorv bullae of T. dumitrescuae are presumablv smaller in comparison to extant species and similar in size to that of amami rabbit ( Pentalagus ). However, the auditorv bullae in the cranial material from MVL are close in size to that of Oryctolagus . Finallv, the mandible of T. dumitrescuae (ZIRS 80457) exhibits a slightlv shorter diastema (index I10, Supporting Information, Fig. S1) compared to MVL, whereas the rest of the mandible does not show anv major dissimilarities.

Te palatal parts of T. meridionalis were recentlv described bv Şen and Geraads (2023). Like MVL, the posterior end of the incisive foramen produces two rounded grooves that are separated bv a pointed mesial palatal spine and extend posteriorlv to the mid-level of the P2s. Te incisive foramen of T. meridionalis is, however, slightlv wider than that of MVL (index I2, Supporting Information, Fig. S1). No major palatine foramen is visible in the Moroccan leporid for a comparison with MVL. In T. meridionalis , the palatal length in relation to the breadth of the choanae exhibits significantlv lower values than in MVL. It is also noteworthv that the absence of the posterior spine of the palate in T. meridionalis is a distinguishing characteristic from the MVL specimens and the majoritv of leporids ( Şen and Geraads 2023). In addition, the choanae of T. meridionalis is wider than that of MVL and the palate of T. meridionalis is shorter than in MVL (index I4, Supporting Information, Fig. S1). Te inter-zvgomatic width in T. meridionalis measures 34.7 mm between the antero-external borders of the zvgomatic arches, falling below the range of the MVL specimens, vet in close proximitv to MVL-52. Like T. meridionalis , the zvgomatic arches of MVL exhibit a slight posterior divergence. In contrast to the sharp ‘V-shaped’ structure of the zvgomatic process of the maxilla in MVL, this feature is less developed in T. meridionalis and not as arched and sharp. Lastlv, the available mandibles of T. meridionalis have a slightlv shorter diastema in comparison to that of MVL (index I10, Supporting Information, Fig. S1).

Finallv, T. raynali from Grote des Rhinocéros exhibits a mandible with a significantlv reduced value for the I10 index when compared to MVL (Supporting Information, Fig. S1). Laterallv, the mandibular bodv below the diastema is shallower in T. raynali . Te mental foramen shows similar development in both taxa. Te mandibular bodv of the Moroccan taxon displavs numerous prominent foramina; in MVL, these foramina appear relativelv subtle, expanding in some cases beneath the p4.

Cladistic results: Te cladistic analvsis (Supporting Information, Appendix S2) provided nine most-parsimonious trees (length: 107; CI: 59; RI: 83) and hence failed to resolve anv relationship apart from the more primitive position of Hypolagus and Alilepus compared to the rest of ingroup taxa, the alreadv known sister-group relationships between North American Syloilagus and Brachylagus (see also: Robinson and Mathee 2005), and the close relationships between Pentalagus and Pliopentalagus (see also: Tomida and Takahasi 2023). Te strict consensus tree is given in the Supporting Information, Figure S2. As in Averianov (1999), Trischizolagus takes part in a wide polvtomv including extant and extinct Pliocene to recent genera from both the New and the Old World.

Although highlv unresolved, in seven out of the nine trees (78%), Trischizolagus is nested in different basal positions within a group including Serengetilagus , Pronolagus , Pliopentalagus , and Pentalagus ± Romerolagus (TS2P ± R group). A deep AIR [character A15(1)] on p3 excludes Romerolagus from the TS2P ± R group and supports the monophvlv of the rest. On the other hand, the common presence of PIR [either as a flexid or fossetid; character A17Rw (1)] excludes Serengetilagus from this group and links the rest of the genera to the more primitive Alilepus , in distinction to other ingroup taxa. Within the TS2P ± R group, the retention of a more primitive P2 with two re-entrants [character A9(1)] discriminates African from non-African taxa.