Introduction

The late Miocene mammal fossiliferous sites of the Axios Valley have been known since the beginning of the last century (Arambourg and Piveteau 1929). A new field campaign in the Axios Valley, started in 1972, has led to the relocation of the previously known localities, the discovery of new ones and the collection of numerous fossils (Koufos 2006a, in press and ref. cited). Among the new localities is Ravin de la Pluie (RPl), situated near the village of Nea Messimvria about 25 km west of Thessaloniki (Fig. 1). The RPl fauna is rich, and its study indicated that it is more primitive than that of Pikermi and the other Greek Turolian faunas, correlated to the late Vallesian, MN 10; the magnetostratigraphic data of the associated deposits suggest an estimated age of ~9.3 Ma (Koufos 2006a; Sen et al. 2000). Although the RPl carnivoran remains are rare in comparison to the other mammal groups of the fauna, their composition is interesting and is comprised of the following taxa: Eomellivora wimani, Adcrocuta eximia leptoryncha, Protictitherium cf. intermedium, Protictitherium aff. gaillardi, ?Hyaenictis sp. and Metailurus parvulus (Koufos 2000, 2011a). Among them is a small-sized hyaenid, described as Protictitherium aff. gaillardi (de Bonis and Koufos 1991; Koufos 2000). The known material of P. aff. gaillardi has been augmented with some new remains, found during the last field expeditions (2004–2009). The present study provides new descriptions of the material and comparisons with the known Eurasian protictitheres to define it more precisely.

Fig. 1
figure 1

Map of Greece with the Protictitherium bearing mammal localities. ANT = Antonios, MN 4/5; DKO = Dytiko 3, MN 13; MLN = Mytilinii-4, MN 11; PNT = Pentalophos 1, ?MN 9; RPl = Ravin de la Pluie, MN 10; XIR = Xirochori 1, MN 10. The map is taken from www.shaded-relief.com

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Materials and methods

The studied material is housed in LGPUT. The material has been measured using a digital caliper, and the measurements are given in mm. The bivariate plots were produced using Excell 2007. The software PAST (Hammer et al. 2001) was used for the Principal Component Analysis (PCA). The lacking measurements of the compared specimens are replaced by column average substitution. In the given analysis specimens lacking more than four measurements are excluded. The morphological comparison is based on direct comparisons of the studied material with original material or casts of the various Eurasian protictitheres.

a.a.c.:

anterior accessory cusp(-id)

BSPM:

Bayerische Staatssammlung fur Pälaeontologie und Historische Geologie, München

ANT:

Antonios, Chalkidiki, Greece

DKO:

Dytiko 3, Axios Valley, Greece

LGPUT:

Laboratory of Geology and Palaeontology, University of Thessaloniki

MLN:

Mytilinii-4, Samos, Greece

MNHN:

Museum national d’Histoire naturelle, Paris

p.a.c.:

posterior accessory cusp(-id)

PNT:

Pentalophos 1, Axios Valley, Greece

RPl:

Ravin de la Pluie, Axios Valley, Greece

XIR:

Xirochori-1, Axios Valley, Greece

Systematic palaeontology

  • Carnivora Bowdich 1821

  • Hyaenidae Gray 1869

  • Ictitheriinae Trouessart 1897

  • Protictitherium Kretzoi 1938

  • Protictitherium thessalonikensis n. sp.

Synonyms

1980 Plioviverrops orbignyi Koufos, p. 67; pl. IX, Fig. 1

1991 Protictitherium aff. gaillardi Bonis and Koufos, p. 368; pl. III, Fig. 2

2000 Protictitherium aff. gaillardi Koufos, p. 59

Locality

Ravin de la Pluie (RPl), Axios Valley, Macedonia, Greece.

Age

Late Vallesian, MN 10, (Late Miocene); GPTS = ~9.3 Ma.

Holotype

Right maxillary fragment with C-M2, RPl-69 (Fig. 2c).

Fig. 2
figure 2

Protictitherium thessalonikensis, Ravin de la Pluie (RPl), Axios Valley, Greece, late Vallesian, MN 10. a. Maxilla with C-M2 dex and P3-P4 sin, RPl-60; a 1 . dorsal, a 2 . lateral, and a 3 . occlusal view. b. Right maxillary fragment with C-P4, RPl-16; b 1 . buccal, b 2 . lingual, and b 3 . occlusal view. c. Right maxillary fragment with C-M2, RPl-69, HOLOTYPE; c 1 . buccal, c 2 . lingual, and c 3 . occlusal view. d. Right mandibular fragment with c-m2, RPl-68; d 1 . buccal, d 2 . lingual, and d 3 . occlusal view

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Paratypes

Maxilla with C-M2 dex and P3-P4 sin, RPl-60; right maxillary fragment with C-P4, RPl-16 (the distal border of the P4 is slightly broken); left P1, RPl-69a; left P2, RPl-69b (these specimens were found together with RPl-69 and possibly belong to the same individual); left P3, RPl-51; right mandibular fragment with c-m2 dex, RPl-68.

Measurements

See Table 1.

Table 1 Dental dimensions of P. thessalonikensis from RPl, Axios Valley, Macedonia, Greece
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Etymology

From the name of the city Thessaloniki, situated near the delta of the Axios River. Thessaloniki was the sister of Alexander the Great, and the city was founded in her honor in 316/15 BC.

Diagnosis

Small size; low cusps(-ids) in the teeth; protocone of the P4 in line with the mesial border of the parastyle; large molars, especially M2; slight buccal projection of the paracone in the M1; strongly molarized p4; strong metaconid and large talonid with high entoconid in the m1.

Differential diagnosis

P. thessalonikensis differs from P. gaillardi in the smaller size, lower main cusps(-ids), presence of the p.a.c. and absence of the mesial cingular projection in the P2,3, stronger parastyle and protocone of the P4, position of the upper carnassial’s protocone, smaller buccal projection of the M1’s paracone, markedly larger M2, absence of the a.a.c. in the p3, more molarized p4, stronger metaconid of the m1, and larger talonid with stronger entoconid of the m1. It differs from P. crassum in the remarkably smaller size, position of the P4’s protocone, weaker p.a.c. of the lower premolars, weaker a.a.c. of the p3,4, relatively larger talonid of the m1, and relatively lower entoconid of the m1.

Description

Except RPl-69, which is a new find, all the other specimens are mentioned in the previous publications for the RPl carnivores (Koufos 1980, 2000; de Bonis and Koufos 1991). The available maxillary fragments preserve only small parts of the skull (Fig. 2), providing little information on its morphology. The most complete specimen is RPl-60, which exhibits crushing and compressing deformation; its morphology is thus difficult to assess (Fig. 2a). The palate of RPl-60 is narrow at the level of the canines and P2, yet widens to a breadth of 37 mm at the distal border of the carnassials (Fig. 2a3). The anterior border of the choanae cannot be detected in the preserved part of the palate; it should be well behind the distal border of the M2. The preserved part of the orbits is strongly deformed; their anterior border is above the middle of the carnassial (Fig. 2a1,2). The infraorbital foramen is large. The upper dentition is better preserved in RPl-69; in RPl-60 the teeth are more worn than in the other two specimens (Fig. 2a). The canine is completely preserved in RPl-16, 69; in RPl-60 only its root is present (Fig. 2). It is high and pointed with an elliptical cross section, a strong mesio-labial crest and a weaker distal one running from the base to its apex, convex buccal and flattened lingual surface, and strong root slightly curved backwards. The P1 is small, single-rooted, monocuspid and with an elliptical crown; its alveole is clearly distinguished in RPl-16, 60 (Fig. 2b3, c3). The P2 has very small p.a.c., strong lingual and weaker buccal cingulum and lacks a.a.c.; in its mesio-lingual corner there is a very small cingular projection, formed from the joining of the basal cingulum with a crest running from the apex to the base of the main cusp. The P3 is similar to P2 but larger and more robust with stronger p.a.c. and cingulum; the lingual cingulum is slightly projected in the distal part of the tooth. The upper carnasial is short and wide with a large and well-separated protocone that does not exceed the mesial border of the parastyle, short and curved buccally metastyle blade, as well as very strong lingual and weaker buccal cingulum. The observed small size difference among the upper premolars of the studied specimens (Table 1) could indicate sexual dimorphism. The M1 is characterized by triangular shape, dominance of the protocone, slight buccal projection of the paracone and the development of a deep fovea between the cusps. In the unworn or slightly worn teeth, the fovea is divided in two parts by a crest from the protocone’s apex to that of the paracone; the anterior fovea is very small. This feature gradually disappears with attrition and the occlusal surface flattens (RPl-60). The M2 is similar to M1, but is smaller and exhibits an elliptical occclusal contour, as its paracone is not buccally projected.

The mandibular fragment RPl-68 preserves part of the horizontal ramus with the toothrow; the canine and p1 are broken, while the alveole of the m2 is clearly distinguished (Fig. 2d3). The mandibular corpus is relatively high, preserving a large mental foramen, situated below the p2. The root of the canine indicates that it has an elliptical transverse section. The p1 is small, single-rooted, and has an elliptical occlusal outline. The p2 lacks a.a.c., but has a well-developed p.a.c., situated in a strong distal projection of the distal cingulum; the latter is strong and elevated distally. The disto-buccal part of the p3 is slightly broken; the tooth is similar to the p2, but it is larger and has a vestigial a.a.c. The p4 has a small but clear a.a.c., while its distal part is talonid-like. The p.a.c. is situated in the buccal border of a strong distal cingular projection, whose lingual part is elevated, giving the appearance of an “entoconid.” The carnassial has a relatively strong and high metaconid, which is slightly lower than the protoconid. The talonid is relatively large and wide with three cuspids; the entoconid dominates. A small cuspid is developed in the middle of the valley between trigonid and talonid, joining their junction with the hypoconid.

Metrical comparison

The available material of the various protictitheres is scarce, and the metrical comparisons are limited. Despite these limitations, using the available dental material and measurements, the RPl sample is compared with the two better known and common Eurasian protictitheres (P. gaillardi and P. crassum) through Principal Component Analysis (PCA) (Fig. 3). The distinction of P. gaillardi-P. aff. gaillardi from P. crassum is clear by Component 1 (PC1) in the PCA for the upper dentition (Fig. 3a). The RPl sample is clearly separated from the above two taxa, situated in the first quadrant of the diagram and in the left limit of PC1 (Fig. 3a). This position of the RPl sample is due to its smaller size and having molars larger than P. gaillardi-P. aff. gaillardi. In the second character the RPl protictithere resembles P. aegaeum, which also has larger molars than those of P. crassum from Spain. In the PCA diagram for the lower dentition (Fig. 3b) PC1 clearly separates the small P. gaillardi-P. aff. gaillardi from P. crassum-P. cf.crassum. The sole RPl specimen is separated from the others by being smaller than P. gaillardi and P. crasum. The metrical comparison of the RPl Protictitherium with the other two taxa indicates that it is smaller than them, representing something different. Further investigation of its size and morphology may lead to its specific determination.

Fig. 3
figure 3

Principal component analysis of the upper (a) and lower (b) dentition of Protictitherium from various localities

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The upper premolars of the RPl sample are clearly smaller than those of P. gaillardi from the European localities, as well as from P. aff. gaillardi from Çandir, Turkey (Fig. 4a, b). The RPl P4, although it is metrically closer to P. gaillardi from the Spanish localities of Hostalets and Can Llobateres, is still smaller than all known material of P. gaillardi (Fig. 4b). On the other hand, the upper molars of the RPl sample are larger than those of P. gaillardi (Fig. 4c, d). The M1 is clearly separated from P. gaillardi by its larger length. The M2 is markedly larger, clearly distinguishing the RPl protictithere from P. gaillardi. The p3 and the lower carnassial are clearly smaller than those of P. gaillardi, while the p4 has similar size to the latter taxon (Fig. 4e, f, g).

Fig. 4
figure 4

Bivariate plot comparing the upper and lower teeth of P. thessalonikensis with P. gaillardi from various Eurasian localities

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Morphological comparison

The metrical comparison of the RPl protictithere with the known material indicates that it is closer to P. gaillardi, as has been previously mentioned (de Bonis and Koufos 1991; Koufos 2000). A precise morphological comparison first with the material of this taxon and then with the other taxa of Protictitherium will provide useful information for its taxonomic determination.

Comparison with the French protictitheres. The type material (maxilla and mandible) of P. gaillardi originates from the locality La Grive and was originally described as Herpestes crassus (Gaillard 1899, p. 60; pl. II, Figs. 1, 3), although it was later transferred to Progenetta gaillardi (Forsyth-Mayor 1903). The materials from La Grive and the taxon Herpestes crassus were considered as the genotype of the new genus Protictitherium (Kretzoi 1938). However, the taxon has long been referred to as Progenetta gaillardi (Viret 1951; Mein 1958; Crusafont-Pairó and Petter 1969) until its transfer to Protictitherium by Schmidt-Kittler (1976). The RPl protictithere differs from the type material of P. gaillardi in the following (Fig. 5a–d): (1) its main cusps(-ids) are lower; (2) the P2,3 lack mesial cingular projection, which is stongly developed in the type material of P. gaillardi, and they bear a clear p.a.c. instead of a distal cingular projection in the type; (3) the carnassial has a stronger parastyle, lower paracone, shorter and more curved buccally metastyle blade and stronger protocone, situated in line with the mesial border of the parastyle; in the type material the protocone clearly exceeds the mesial border of the parastyle; (4) the M1 has a less buccally projected paracone and stronger protocone; (5) the M2 is remarkably larger; (6) the p3 lacks a.a.c., while in the type there is a vestigial one; (7) the p4 has stronger p.a.c., as well as stronger and more elevated lingual projection of the disto-lingual cingulum, suggesting higher molarization than the type; (8) the lower carnasial has a stronger metaconid and larger talonid with stronger entoconid; the talonid’s dimensions are 4.92 × 4.91 mm in RPl-68 and 2.53–3.68 × 3.50–4.22 in P. gaillardi.

Fig. 5
figure 5

Comparison of the upper dentition of P. thessalonikensis with P. gaillardi from various Eurasian localities. a–c. P. gaillardi, Ravin de la Pluie, Greece; d. P. gaillardi, La Grive, France; e. P. gaillardi, Antonios, Greece; f, g. P. gaillardi, Can Llobateres, Spain (casts); h. P. aff. gaillardi, Çandir, Turkey

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In addition to La Grive, P. gaillardi is also known from the French localities of Simorre and En Pejouan. Two mandibular fragments are known from En Pejouan, housed in MNHN (Fig. 6b). The RPl-68 mandible, besides being smaller, differs from this material in its lower main cuspids, weaker a.a.c. of the p4, larger talonid and weaker entoconid of the m1 (Fig. 6a, b). A mandibular fragment of P. gaillardi from Simorre is also housed in MNHN (Fig. 6c); it has similar differences from the RPl-68 as those referred to above (Fig. 6a, c).

Fig. 6
figure 6

Comparison of the lower dentition of P. thessalonikensis with P. gaillardi from various Eurasian localities. a. P. gaillardi, Ravin de la Pluie, Greece; b. P. gaillardi, En Pejouan, France; c. P. gaillardi, Simorre, France; d. P. gaillardi, La Grive, France; e. P. gaillardia form-A, Arroyo, Spain (cast); f. P. gaillardia form B, Can Ponsich, Spain (cast). 1. buccal, 2. labial and 3. occlusal view

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The type material of P. crassum also originates from the locality La Grive. It was originally described as Herpestes crassus based on some mandibular remains (Depéret 1892 p. 31; pl. I, Figs.14–17); for its history and synonyms, see Werdelin and Solounias (1991). Based on the description and illustrations of the type material (Depéret 1892; Viret 1951; Mein 1958), P. crassum differs from the RPl protictithere in the larger size (Figs. 3, 4), the position of the carnassial’s protocone (it is situated in front of the mesial border of the parastyle), the stronger p.a.c. of the lower premolars, the stronger a.a.c. of the p3,4, and the relatively smaller talonid and lower entoconid of the m1.

Comparison with the Greek protictitheres. The Greek protictitheres are referred to two main taxa P. gaillardi and P. crassum, while an isolated m1 from RPl is referred to P. aff. intermedium (Koufos 2006a, 2011b). A maxillary fragment with P4-M1 dex and a mandibular fragment with p4 sin of P. gaillardi have been described from the early/middle Miocene locality of Antonios (Koufos 2008). The RPl M1 is larger than that of Antonios, with a less buccally projected paracone and a larger protocone (Fig. 5a, b, e). P. crassum is known from two localities of the Axios Valley; a mandible has been reported from XIR and a hemimandible from DKO (Koufos 2000). The weaker p.a.c. of the premolars, the weaker a.a.c. of the p4 and the relatively stronger metaconid of the m1 distinguish the RPl material from the XIR and DKO P. crassum. Two mandibular fragments from the locality PNT of the Axios Valley are referred to P. cf. crassum (Koufos 2000). Their larger size, more molarized p4, relatively higher and more pointed cuspids, and stronger a.a.c. of the p4 separate them from RPl-68. Recently, P. crassum was recognized in the locality MLN of Samos from a mandible with almost complete dentition (Koufos 2009). The larger size and more molarized premolars of the Samos specimen distinguish it from the RPl-68.

Comparison with the Spanish protictitheres. The protictitheres are quite common in Spain, referred from several localities with P. gaillardi and P. crassum (Crusafont-Pairó and Petter 1969; Petter 1976). P. gaillardi is known from the locality of Can Llobateres by a maxillary fragment with P3-P4 dex and another with M1-M2 dex (Petter 1976). A direct comparison of the studied RPl sample with these specimens indicates that the former has weaker p.a.c. in the P3, a protocone in line with the mesial border of the parastyle in the P4, a less buccally projected paracone and a stronger protocone in the M1, as well as a significantly larger M2 (Fig. 5a–c, f, g). A mandibular fragment with p3-m1 from the locality Arroyo del Val IV was described as P. gaillardi form A (Crusafont-Pairó and Petter 1969). Besides its smaller size, the RPl protictithere differs from Arroyo P. gaillardi in the absence of a.a.c. in the p3 (the Arroyo p3 has a vestigial a.a.c.), the significantly weaker a.a.c. and p.a.c. of the p4 (in RPl-68 the a.a.c. is rudimentary), the stronger and elevated lingual projection of the disto-lingual cingulum of the p4 (more molarized) and the relatively lower parastylid and paraconid, stronger metaconid, stronger and wider talonid and stronger entoconid of the m1 (Fig. 6a, e). Another mandibular fragment of P. gaillardi from the locality Can Ponsich was described as P. gaillardi form B (Crusafont-Pairó and Petter 1969). The comparison of the RPl-68 dentition with a cast of this specimen indicates the same differences as those seen in Arroyo material (Fig. 6a, f). P. crassum is also well known in Spain from several localities (NOW 2011). Some maxillary and mandibular remains from Can Bayona are described as P. crassum llopisi (Crusafont-Pairó and Petter 1969). The slenderer P3 (Table 1), the weaker p.a.c. and cingulum of the P3, the protocone in line with the mesial border of the parastyle in the P4, the weaker p.a.c. of the lower premolars, the weaker a.a.c. of the p3,4 and the relatively stronger metaconid in the m1 of the RPl protictithere, as well as its smaller size, distinguish it from Can Bayona P. crassum.

Comparison with the Asia Minor protictitheres. In Turkey P. gaillardi is known from Paşalar by a p4 and m1 described as P. aff. gaillardi (Schmidt-Kittler 1976). The dental comparison with RPl-68 indicates that the RPl p4 has smaller p.a.c., as well as more lingually projected and elevated disto-lingual cingulum, while the RPl m1 has smaller talonid with relatively smaller metaconid and entoconid; the dimensions of the talonid are 3.2 × 4.1 mm in Paşalar m1 versus 4.92 × 4.91 in RPl-68. A maxillary fragment with M1-M2 dex from Çandir is described as P. aff. gaillardi (Schmidt-Kittler 1976). The RPl molars are larger (especially the M2), and the paracone of the M1 is less buccally projected than that of the Çandir specimen (Fig. 5a–c, h). Two mandibular fragments of P. aff. gaillardi are also known from Çandir (Nagel 2003). Based on the illustrations of Nagel (2003: pl. 2, Fig. 2), their larger size, stronger a.a.c. of the p2,3 and higher main cuspids of the m1 distinguish it from RPl-68. P. crassum is reported from the localities Sofça, Akçakoy and Mahmutgazi (Schmidt-Kittler 1976). It has similar differences from the RPl sample as those referred to above. A new protictithere was described from the locality Esendere (Karaburum Peninsula) under the name P. aegaeum (Kaya et al. 2005). It is larger (size of P. crassum) and clearly distinguished from the RPl sample; according to the authors it is closely related to P. crassum from which it differs in the high p4 and the high trigonid of the m1.

Some mandibular remains of a small-sized protictithere, named P. intermedium, are known from the localities of Çandir and Paşalar (Schmidt-Kittler 1976). Comparison of the RPl-68 with its holotype (BSPM-1968II-736), in addition to the larger size of the former, shows some morphological differences. The RPl p2 has a lower main cuspid and a large distal cingular projection with a clear p.a.c. In P. intermedium the p2 lacks p.a.c. or cingular projection, but it bears two vestigial prominences in the distal border of the main cuspid and a rudimentary distal projection of the distal cingulum; moreover, in its mesiolingual base there is a vestigial cingular projection, which is absent in RPl-68. There are no substantial morphological differences in their carnassials. However, the cuspids of RPl-68 are higher, and the valley distinguishing the trigonid from talonid is deeper in the m1 of P. intermedium. A mandibular fragment from Paşalar (BSPM-1968VI-735) is also referred to P. intermedium (Schmidt-Kittler 1976). It has similar size to the holotype of the taxon, and it is smaller than RPl-68.

Another small-sized protictithere from Turkey is P. cingulatum, described from the locality of Eskihisar on some mandibular remains (Schmidt-Kittler 1976). In comparison to RPl-68, besides its smaller size, it has a relatively stronger p.a.c. in the p2, an a.a.c. in the p3 (absent in RPl-68), relatively stronger a.a.c. in the p4, relatively smaller talonid in the m1 and stronger cingulum in all teeth. The upper dentition of P. cingulatum is only known by an isolated P3 and a single M1. The P3 has similar size and morphology to the RPl one, but it has a much stronger lingual cingulum. The M1 of P. cingulatum is smaller with stronger buccal projection of the paracone and a less developed metacone than those of the RPl one. The smaller size and especially the strong cingulum distinguish P. cingulatum from the RPl material.

Conclusion

The locality RPl of the Axios Valley is well known because of the presence of the hominoid primate Ouranopithecus macedoniensis (Koufos 2006, in press and ref. cited). The RPl mammal fauna is rich, dominated by bovids and giraffids with several equids, a few carnivores and rare rhinos. The Vallesian palaeoenvironment of the Axios Valley and the wider area of the Eastern Mediterranean was open (savannah-like) with some small trees, shrubs, bushes and thick grass (de Bonis et al. 1992, 1999; Koufos 2006b; Merceron et al. 2005, 2007; Koufos and Konidaris 2011).

The protictitheres were unknown in Greece until the beginning of the 1980s when they were recognized in the DKO fauna of the Axios Valley by a hemimandible of P. crassum (Koufos 1980). During the following decades, more material has been unearthed from the various Axios Valley localities, enriching our knowledge about their diversity in Greece (de Bonis and Koufos 1991; Koufos 2000); recently, they were traced in the locality MLN of Samos Island (Koufos 2009). Except for the DKO and MLN protictitheres, which are dated to the Turolian, all the others originate from the Vallesian localities of PNT, XIR and RPl (Koufos 2000). The first RPl protictithere was the specimen RPl-16, which was described as Plioviverrops orbignyi (Koufos, 1980), the only known small hyaenid taxon from Greece at that time. This specimen, as well as the RPl-51, 60 and 68 have been referred to P. aff. gaillardi because of their smaller size (de Bonis and Koufos 1991; Koufos 2000). Despite some differences with that species a new species was not originally proposed for the RPl material, since the known material of the Eurasian protictitheres at that time was scanty and fragmentary with several synonymies and high taxonomic inflation (de Bonis and Koufos 1991; Koufos 2000). Three possibilities have been considered for the RPl protictithere. Either it is a new species or subspecies, or a P. gaillardi with great geographic and stratigraphic distribution (Koufos 2000). The discovery of the maxillary fragment RPl-69 offered the opportunity for a re-examination of this material and for comparisons with several protictithere remains, housed in MNHN and BSPM, as well as with some Spanish material. This comparison showed clear morphological differences from P. gaillardi and allows the recognition of a new species, named Protictitherium thessalonikensis n. sp.