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Pachynolophus ruscassierensis n. sp. (Figs 8, 9) TYPE SPECIMEN (HOLOTYPE). ��� UM-AUM 231 fragmentary skull preserved from nasal opening up to zygomatic arch, with right (alv. C/-P1/)-P2/-M3/ and left (alv. C/, P2/)-P3/-M3/ (Fig. 8B). TYPE LOCALITY. ��� Aumelas, H��rault department, France. ETYMOLOGY. ��� From the geographic locality; in Occitan language, ���ruscassier��� evokes a place covered with trees having rough bark. MATERIAL. ��� AUM 48, left M1/; AUM 70, left P3/; AUM 138, right maxillary fragment with P4/-M2/; AUM 176, right M1/; AUM 186, left DP3/; AUM 187, left M1/; AUM 189, left M2/; AUM 191, right M1/; AUM 194, left M1/; AUM 197, M1/; AUM 210, right maxillary fragment with M3/; AUM 211, right M2/; AUM 216, left maxillary fragment with M1/-M2/; AUM 224, left M3/; AUM 235, left M1/ (cast); AUM 304, right M3/; AUM 321, left maxillary fragment with (M1/)-M2/; AUM 324, left maxillary fragment with M3/; AUM 1544, palate with right (alv. C/)-P1/, M1/-M3/ and left P1/, P4/-M3/; AUM 1545, AUM 1546, AUM 1564, left M1/-M2/; AUM 1552, left maxillary fragment with P2/- (M3/); AUM 1553, left maxillary fragment with P3/-M2/; AUM 1554, right maxillary fragment with P4/-M2/; AUM 1555, right M2/; AUM 1563, right maxillary fragment with M2/-M3/; AUM 1565, left M2/; AUM 1566, right P3/; AUM 1567, left P4/; AUM 1618, right maxillary with DP2/-DP4/-M1/; AUM 1619, fragment of dislocated skull with right M1/-M2/; AUM 1628, left P3/-(M2/) (composite���); AUM 1632, right P3/; AUM 1634, left M3/. AUM 161, left mandible with M/1-M/3, alveoli of P/1-P/4; AUM 167, mandible with symphysis, left P/1- P/2 and both canines; AUM 169, right mandible fragment with M/1-M/3, alveoli of P/3-P/4; AUM 177, left mandible fragment with M/1; AUM 178, right P/3; AUM 185, right M/2; AUM 217, right M/2; AUM 305, left M/2; AUM 1549, right DP/4; AUM 1556, right mandible with (alv. DP/2)-DP/3-M/2; AUM 1558, right M/2; AUM 1559, left M/1; AUM 1562, AUM 1612, right P/2; AUM 1568, right mandible with M/2-M/3; AUM 1569, right M/3; AUM 1570, left M/2- (M/3); AUM 1571 right fragment with M/3; AUM 1575, right M/1; AUM 1578, AUM 1637, right P/3; AUM 1579, right P/1; AUM 1582, AUM 1621, AUM 1639, right M/1; AUM 1605, left mandible with (DP /3)-DP/4-M/2; AUM 1623, left M/1; AUM 1629, AUM 1636, AUM 1640, AUM 1642, AUM 1643, right P/4; AUM 1630, left DP/4; AUM 1631, AUM 1635, left (M/3); AUM 1638, right M/3; AUM 1641, right M/1; AUM 1657, left M/2. DIAGNOSIS. ��� Rather large Pachynolophus species, LRDJ = 51- 53 mm; estimated weight about 21 kg. Buno-lophodont dentition. Ectoloph of upper molars fairly flat, devoid of mesostyle and usually without pseudomesostyle. Deeply hollowed centrocrista. Relative surface of the premolar area not greatly reduced for a Pachynolophus, estimated at 44% of that of molars. Transversally elongated upper premolars, but with a lingual contour not specially narrowed. Rather straight lophids on lower molars; the transverse ones dug at midway. Labial crest of the M/3 hypoconulid connected to the mid hypolophid. Relatively thick and high cingula, almost wholly surrounding upper premolars, only missing on lingual side of lower molars. DPC of variable length but generally less elongated than in most other Pachynolophus. DIFFERENTIAL DIAGNOSIS. ��� Larger than most Pachynolophus species, except Pa. cayluxi. More lophodont dentition than that of Pa. eulaliensis and Pa. cesserasicus, but much less than that of Pa. lavocati and Pa. zambranensis. Centrocrista of upper molars more dug than those of Pa. bretovensis and Pa. garimondi. Greater relative surface of the premolar area than that of Pa. molipontiensis, Pa. livinierensis, Pa. cesserasicus and Pa. lavocati. Less transversally elongated P4/ than in Pa. cayluxi, Pa. gaytei and Pa. cesserasicus with a less narrow lingual outline. Presence of a distinct metaconule on P4/, contrary to Pa. boixedatensis and M3/ not so large. Postero-lingual basin of P4/ less broad than that of Pa. bretovensis and Pa. garimondi. Thicker and higher cingula than in these latter species, wider also than in Pa. duvali. DESCRIPTION Upper cheek teeth The type-specimen AUM 231 is in very good condition; only the M1/ bears notable signs of wear. It is a medium-sized Pachynolophinae (LRDJ = 51.3 mm), slightly smaller than Propalaeotherium sudrei but larger than most hyracotheres. Dimensions of the whole material reported to the taxon suggest a body weight of about 21 kg following the equations in Janis (1990) (Appendix 8), with coefficients of size variability (V) mostly Pachynolophus (Remy 1972). On AUM 231, the ratio SP/SM is estimated at 44 (Appendix 21) and the PMI at 65.7. P4/ is transversely elongated; the labial bulge of paracone and metacone is very marked and the centrocrista of ectoloph less notched than on molars. P3/ has an identical shape, but it is slightly less transversally elongated, with closer outer cusps and less notched centrocrista. As molars, the premolars exhibit some morphological variability. Indeed, some premolars differ markedly from homologous teeth of the holotype. Thus, some P3/ and P4/ have a pronounced concavity of the labial outline (AUM 1553, AUM 1628). There is a strong labial cingulum on the P3/-P4/ of AUM 231, continuous and extended by a poorly developed parastyle. The latter can still be weaker (AUM 1544, AUM 1554 [P4/], AUM 1552, AUM 1566 [P3/]). The protocone of P3/-P4/ is generally axially located. It is slightly shifted forward on AUM 231, and even more forward on some P3/ (AUM 1552). The paraconule of these teeth is bulbous on AUM 231, rather separated from the protocone and clearly lower. It is weaker with the groove between paraconule and protocone being shallower on other specimens (AUM 1554 AUM 1567, AUM 1628). The rounded metaconule is labially extended by a thin rectilinear postprotocrista ridge oriented toward the centrocrista on AUM 231. The transverse lophs are more V-shaped with less distinct conules on AUM 1552 and AUM 1553. On the holotype, a thick and continuous cingulum surrounds the whole inner part of P3/-P4/ up to the ectoloph, but without any enlargement of a posterior basin unlike in some P3/ (AUM 1552, AUM 1553). The lingual cingulum is weaker and interrupted at protocone level on some P4/ (AUM 1554, AUM 1567) or P3/ (AUM 1552, AUM 1553). The P 3/ (AUM 70), which displays a particularly weak and low metaconule, has a forward shifted protocone and lacks lingual cingulum. A P2/ is preserved on the holotype. It is a small ovoid tooth, narrow mesially and wide distally. It has two very close labial cusps with the metacone hard to individualize and lower than the paracone. The other known P2/ (AUM 1552) is a bit smaller and more rounded in shape. Its high labial cusp is extended distally by a crest devoid of any hint of an incipient metacone. The ectocingulum is faint and the styles poorly defined on AUM 231. The oblique lingual cingulum is enhanced by a small elongated protocone. In the distal basin, a tiny and very low crest evokes a faint preprotocrista. On AUM 1552, the protocone is more individualized and there is no crest in the worn basin. The P1/ are preserved on AUM 1544. They are simple narrow teeth with a prominent cusp barely shifted rostrally and a surrounding cingulum. It seems that there was place for a short diastema between P1/ and P2/. The presence of a P1/ is also attested on AUM 231 by two alveoli indicating a tooth as long but narrower than P2/. There was no P1/-P2/ diastema on this specimen. The alveolus of upper canine indicates a large and rather narrow tooth. The deciduous dentition is known by an upper jaw (AUM 1618), whose teeth are unfortunately fractured and crumbled, and by a DP3/ (AUM 186). The DP4/ is molarized, has a high and rather protruding parastyle and lacks a mesostyle. The groove between paracone and protocone appears rather deep. The hypocone is less lingual in position than the protocone. The lingual cingulum is narrow and interrupted on hypocone. The DP3/ are also molariform but with a slightly oblique mesio-lingual outline. On AUM 186, the protocone is shifted labially relative to hypocone and slightly lower, with a deep lingual notch between protocone and hypocone. The paracone-protocone groove is shallower than on AUM 1618. The metaloph is curved on AUM 186 due to the presence of a small accessory distal cusp. The cingulum is thick and high, surrounding the tooth and only slightly broken at the paracone. DP2/ is an elongated narrow triangular tooth. The paracone is prominent with a close low metacone. The parastyle is welldeveloped like an anterior cusp. The inner part of the tooth is chipped. DP1/, which is not preserved, had two roots. Lower cheek teeth (Fig. 9) The lower molars are characterized by rather pointed crescents. The lophids are rather straight and lophodont. The transverse ones appear to be dug midway when unworn. The trigonid is rather short, even shorter than talonid. The preprotocristid is lowered, and curved mesially, without any trace of paraconid. The metaconid is clearly splitted. The metalophid is connected between metaconid and metastylid. The hypoconulid is well developed on the middle of distal edge of M/1 and M/2. The labial crest of hypoconulid of M/3 reaches the middle of hypolophid and the curved lingual crest bears small knobs (AUM 161, AUM 169). The ectocingulum of molars is usually well marked, relatively high (about 2 mm for a total unworn cusp height of 6 mm on AUM 161) and fairly continuous (AUM 161, AUM 217), but can be weaker and more or less interrupted on cuspids (AUM 169, AUM 185, AUM 1568, AUM 1605). Not any lower molar bears a lingual cingulum. The lower premolars are known only by isolated teeth. Those that we interpret as P/4 (see material) are rectangular and generally not narrowed mesially. The trigonid is molariform with a split metaconid (AUM 1640). The mesial crest of the protoconid is lowered; on AUM 1640 it terminates by a small, split paraconid. The talonid is slightly lower than the trigonid. The hypoconid is shifted labially. Although there is no entoconid, the hypoconid is sometimes extended by a low lingual cristid, a weak clue of an incipient cuspid (AUM 1642). The ectocingulum is generally weak, sometimes restricted to the medivallum (AUM 1629, AUM 1643). P/3 has an identical morphology, but the tooth tapers anteriorly, thus the trigonid is narrower than the talonid and somewhat more flattened (AUM 178). Like on P/4, the hypoconid is shifted labially, without any entoconid. The ectocingulum is rather weak. Three P/2 could be assigned to the species. They are simple teeth with one prominent cuspid (protoconid) slightly shifted rostrally. A parasagittal mesial ridge and a slightly linguo-distal one represent the relicts of the trigonid crescent. On AUM 1612, both ridges end with a very small knob. There is no true talonid, only another low parasagittal crest behind protoconid, terminated by a very small tubercle equivalent to a vestigial hypoconid. The ectocingulum is noticeable, but stopped on protoconid. P/1 (AUM 167), is an even more simple, bi-rooted tooth. The canines, also present on that specimen, are small suggesting it belongs to a female. The most complete canine (on the right) is eroded by a large distal surface of wear. DP/4 is molariform but can be slightly narrow mesially (AUM 1605). It differs from the molars by the lower crown height and the thinness of the enamel (AUM 1630). The paralophid is devoid of a paraconid and the metaconid is clearly split. The talonid is as high as the trigonid and the entoconid as large as the hypoconid. The presence of an hypoconulid is noticeable. The ectocingulum is weak and interrupted on cuspids. DP/3 is narrow mesially but the crescent of the trigonid is fully developed (AUM 1556). An accessory small cuspid is observed on the lingual side of the mesial cristid of the protoconid. The talonid is wide and the entoconid is as high as the hypoconid like on DP/4. Other anatomical data The length of the post-canine diastema (DPC) appears variable in the sample. On a maxilla (AUM 231), it is relatively short (17 mm, i.e. 33% of the length of the cheek teeth row LRDJ [LP2/-M3/], Appendix 20A), but on AUM 1544, it could have exceeded 50% of LRDJ. On mandibles, the length of the DPC can only be known indirectly on AUM 161, which preserves the molar row but is crushed in the premolar region. With a molar length of 33.6 mm and assuming a PMI between 0.67 and 0.70 (an average value for a Pachynolophus), the LRDJ length can be estimated at 56-57 mm. Furthermore, the socket of the canine is missing and the part of the DPC preserved until the anterior alveolus of P/2 is 23 mm long. The DPC would not therefore have been lower than 40 or 41% of LRDJ. With a length of 33 mm, the DPC of AUM 167 would have had a greater relative value, probably over 50% (Appendix 20B). Pachynolophus ruscassierensis n. sp. P2/ P3/ P4/ M1/ M2/ M3/ L W L W L W L W D d L W D d L W D d N 2 2 7 7 8 8 18 18 17 19 18 19 18 18 11 11 11 11 mean 6.3 5.7 7.8 9.4 8.3 10.4 9.8 11.8 12.5 11.6 10.9 12.9 13.7 12.5 11.1 13.0 13.8 12.7 variation 6.0- 5.5- 7.1- 9.1- 7.3- 9.4- 9.0- 10.2- 10.8- 10.3- 9.2- 10.1- 11.1- 10.1- 10.3- 12.1- 12.6- 11.4- range 6.5 5.8 8.5 9.9 9.2 11.6 10.7 13.2 14.6 12.9 12.2 14.7 15.9 14.2 12.1 14.3 15.4 13.9 standard ��� ��� 0.549 0.263 0.657 0.856 0.554 0.766 0.995 0.871 0.939 1.292 1.374 1.371 0.662 0.737 0.962 0.885 deviation coeff. of ��� ��� 7.0 2.8 8.0 8.3 5.7 6.5 8.0 7.5 8.6 10.0 10.0 11.0 5.9 5.7 6.9 7.0 variation DP2/ DP3/ DP4/ L WD d L WD d L WD d N 1 1 1 1 2 2 2 2 1 1 1 1 mean 7.4 5.9 8.7 5.8 9.0 10.0 10.5 9.8 9.5 11.2 11.9 11.5 variation range ��� ��� ��� ��� 8.9- 9.8- 10.4- 9.7- ��� ��� ��� ��� 9.0 10.1 10.6 9.8 upper series LDPC LP2-M3 %DPC LP2-P4 LM1-M3 PMI N 2 2 2 4 3 3 mean 22.3 52.2 42.5 21.8 31.9 68.4 variation range 17.0-27.5 51.3-53.1 33.1-51.8 20.5-22.6 31.2-32.4 65.7-69.4 P/2 P/3 P/4 M/1 M/2 M/3 L W1 W2 L W1 W2 L W1 W2 L W1 W2 L W1 W2 L W1 W2 W3 N 3 3 3 3 3 3 5 5 5 12 12 11 11 11 11 7 9 8 7 mean 7.3 3.8 4.1 8.1 4.6 5.4 9.0 5.7 6.0 9.1 5.9 6.2 10.7 7.0 7.0 14.2 6.8 6.3 4.9 variation 6.7- 3.7- 3.8- 7.2- 4.3- 5.2- 8.3- 5.1- 5.5- 8.3- 5.4- 5.9- 9.4- 6.1- 6.5- 13.4- 6.2- 5.6- 4.3- range 7.6 3.9 4.3 8.7 4.7 5.8 9.3 6.0 6.2 10.2 6.5 6.8 12.4 8.1 7.8 15.2 7.7 7.1 5.9 standard 0.520 0.100 0.265 0.814 0.231 0.321 0.412 0.356 0.277 0.550 0.291 0.401 0.927 0.625 0.395 0.655 0.559 0.677 0.568 deviation coeff. of 7.1 2.6 6.5 10.0 5.1 5.9 4.6 6.2 4.6 6.0 4.9 6.5 8.7 8.9 5.6 4.6 8.3 10.8 11.5 variation DP/2 DP/3 DP/4 L W1 W2 L W1 W2 L W1 W2 N ��� ��� ��� 1 1 1 3 4 3 mean ��� ��� ��� 7.9 4.5 5.7 8.5 5.4 5.6 variation range ��� ��� ��� ��� ��� ��� 8.3-8.7 5.1-6.0 5.4-5.9 standard deviation ��� ��� ��� ��� ��� ��� 0.208 0.403 0.252 coeff. of variation ��� ��� ��� ��� ��� ��� 2.5 7.4 4.5 lower series LDPC LP2-M3 %DPC LP2-P4 LM1-M3 PMI N 1 1 1 1 2 1 mean> 23.0 56.7> 41.0 22.5 34.2 67.0 variation range ��� ��� ��� ��� 33.6-34.8 ��� In the Aumelas sample neither the deepness of the nasal notch on the skull, nor the shape of the premaxillary vertical apophysis are known. The FIO is rather rostrally situated, at 7 mm above P3/ (AUM 231, AUM 1552). On the juvenile AUM 1618, it appears above DP2/. The anterior edge of the orbit (O) levels the mesial border of M2/. The orbital floor is very low (HTMX about 5 mm), and moreover hilly by the relief of the roots of the last molars. The palate is slightly crushed (AUM 231) but appears hollow. It seems neverthe- less have been rather narrow after correction of that crash (taking into account the position of the spine of the median raphe). The maxillary zygomatic process, which is not very dorso-ventrally high (7 mm at orbit level) is expanded laterally, but the bow does not seem to have strongly diverged at the back, like on Pachynolophus livinierensis. On AUM 161, the mandibular body is not very high and only increases slightly backwards (13.3 mm under DPC; 16.8 mm under P/2; 23.4 mm under M/3). The values are close for AUM 169. On the juveniles AUM 1556 and AUM 1605, the mandibular height increases from 16 mm under DP/ 3 to 18 mm under M/2. Two mental foramina are noticeable, one under the limit P/3-P/4 and the second under P/1-P/2 (AUM 161). The vertical ramus is not preserved in Aumelas s, Published as part of Remy, Jean A., Krasovec, Gabriel, Lopez, ��ric, Marandat, Bernard & Lihoreau, Fabrice, 2019, The Palaeotheriidae (Equoidea, Perissodactyla, Mammalia) from the Eocene fauna of Aumelas (H��rault department, France), pp. 525-585 in Geodiversitas 41 (13) on pages 537-543, DOI: 10.5252/geodiversitas2019v41a13, http://zenodo.org/record/3699849, {"references":["JANIS C. M. 1990. - Correlation of cranial and dental variables with body size in ungulates and macropodoids, in DAMUTH J. & MACFADDEN B. J. (eds), Body size in mammalian paleobiology: Estimation and biological implications. Cambridge University Press, Cambridge, New York: 255 - 299 + appendices 16 - 8 to 16 - 10. https: // doi. org / 10.1007 / BF 02192193","REMY J. A. 1972. - Etude du crane de Pachynolophus lavocati n. sp. (Perissodactyla, Palaeotheriidae) des Phosphorites du Quercy. Palaeovertebrata 5 (2): 45 - 78. https: // doi. org / 10.18563 / pv. 5.2.45 - 78","SAVAGE D. E., RUSSELL D. E. & LOUIS P. 1965. - European Eocene Equidae (Perissodactyla). University of California Publications in Geological Sciences, vol. 56, 94 p.","GODINOT M., LABARRERE H. - P., ERFURT J., FRANZEN J. L., LANGE- BADRE B., DE LAPPARENT DE BROIN F. & VIDALENC D. 2018. - Un nouveau gisement a vertebres eocenes, Rouzilhac (MP 10 - 11), dans la serie molassique d'Issel (Aude, France). Revue de Paleobiologie 37 (1): 141 - 333.","REMY J. A. 2017. - Critical comments on the genus Propachynolophus Lemoine, 1891 (Mammalia, Perissodactyla, Equoidea). Palaeovertebrata 41 (1) - e 3: 1 - 18. https: // doi. org / 10.18563 / pv. 41.1. e 3"]}

Genus Pachynolophus Pomel, 1847 TYPE SPECIES. ��� Pachynolophus duvali Pomel, 1847 by original designation. INCLUDED SPECIES. ��� Pa. cesserasicus Gervais, 1849; Pa. cayluxi (Filhol, 1888); Pa. livinierensis Savage, Russell & Louis, 1965; Pa. garimondi Remy, 1967; Pa. boixedatensis Crusafont & Remy, 1970; Pa. lavocati Remy, 1972; Pa. bretovensis Remy, 1988; Pa. molipontiensis Checa-Soler, 1994; Pa. zambranensis Badiola, Pereda-Suberbiola & Cuesta, 2005; Pa. eulaliensis Danilo, Remy, Vianey-Liaud, Marandat, Sudre & Lihoreau, 2013; Pa. gaytei Remy, 2015. EXCLUDED SPECIES. ��� Pachynolophus hookeri Hooker, 1994 (synonym of Cymbalophus hookeri Godinot, 1987; see Danilo et al. 2013). EMENDED DIAGNOSIS (after Danilo et al. 2013). ��� Small brachyodont equoids; nasal notch opening above the postcanine diastema, close to canine; confluent foramen ovale and middle lacerate foramen. Usually rather long DPC. Virtually complete set of cheek teeth with occasional lost of P1/ 1 in old individuals. Less bunodont dentition than in hyracotheres, up to fully lophodont. Mesostyle missing on upper molars, sometimes replaced by a ���pseudomesostyle���. Fairly developed conules. Generally weak cingula, less continuous and less high than in hyracotheres, phyletically tending to fade; the labial one frequently interrupted at paracone on upper molars. Non-molariform premolars with phylogenetic trend toward a reduction of their area relatively to molars. P3/-P4/ devoid of hypocone. Postero-lingual expansion of the distal outline of P4/ in some species. Twinned metaconid on lower molars. Large hypoconulid basin on M/3, with labial cristid of hypoconulid directed from entoconid to mid hypolophid. P/3-P/4 devoid of entoconid. NOTE Occasional absence of the first premolar on some specimens (e.g. FSL 3038 [Pa. livinierensis], ICP 3070 [Pa. boixedatensis]) could be ontogenetic in origin. This phenomenon was also observed in the genus Plagiolophus that bears relatively short premolar series like Pachynolophus (Remy 2004: 123). Indeed, many specimens of various Pachynolophus species retain their P1/1, what may be the original condition (e.g. Pa. cesserasicus FSL 2977, Pa. duvali MNHN CGR-82, Pa. lavocati MNHN Qu-7371, Pa. eulaliensis UM-SEL 45, SEL 88, SEL 05, an unpublished skull of Pa. livinierensis in the Vidalenc��� coll.)., Published as part of Remy, Jean A., Krasovec, Gabriel, Lopez, ��ric, Marandat, Bernard & Lihoreau, Fabrice, 2019, The Palaeotheriidae (Equoidea, Perissodactyla, Mammalia) from the Eocene fauna of Aumelas (H��rault department, France), pp. 525-585 in Geodiversitas 41 (13) on page 537, DOI: 10.5252/geodiversitas2019v41a13, http://zenodo.org/record/3699849, {"references":["SAVAGE D. E., RUSSELL D. E. & LOUIS P. 1965. - European Eocene Equidae (Perissodactyla). University of California Publications in Geological Sciences, vol. 56, 94 p.","REMY J. A. 1972. - Etude du crane de Pachynolophus lavocati n. sp. (Perissodactyla, Palaeotheriidae) des Phosphorites du Quercy. Palaeovertebrata 5 (2): 45 - 78. https: // doi. org / 10.18563 / pv. 5.2.45 - 78","REMY J. A. 1988. - Le gisement du Bretou (Phosphorites du Quercy, Tarn-et-Garonne, France) et sa faune de Vertebres de l'Eocene superieur. VIII. Perissodactyles. Palaeontographica A 205: 155 - 172.","REMY J. A. 2015. - Les Perissodactyles (Mammalia) du gisement Bartonien superieur de Robiac (Eocene moyen du Gard, Sud de la France). Palaeovertebrata 39 (1): 1 - 98. https: // doi. org / 10.18563 / pv. 39.1. e 3","HOOKER J. J. 1994. - The beginning of the equoid radiation. Zoological Journal of the Linnean Society 112: 29 - 63. https: // doi. org / 10.1111 / j. 1096 - 3642.1994. tb 00311. x","GODINOT M., CROCHET J. - Y., HARTENBERGER J. - L., LANGE- BADRE B., RUSSELL D. E. & SIGE B. 1987. - Nouvelles donnees sur les mammiferes de Palette (Eocene inferieur, Provence). Munchner geowissenschaftliche Abhandlungen A (10): 273 - 288.","DANILO L., REMY J. A., VIANEY- LIAUD M., MARANDAT B., SUDRE J. & LIHOREAU F. 2013. - A new Eocene locality in southern France sheds light on the basal radiation of Palaeotheriidae (Mammalia, Perissodactyla, Equoidea). Journal of Vertebrate Paleontology 33 (1): 195 - 215. https: // doi. org / 10.1080 / 02724634.2012.711404","REMY J. A. 2004. - Le genre Plagiolophus (Palaeotheriidae, Perissodactyla, Mammalia): Revision systematique, morphologie et histologie dentaires, anatomie cranienne, essai d'interpretation fonctionnelle. Palaeovertebrata 33 (1 - 4): 17 - 281. https: // doi. org / 10.18563 / pv. 37.1 - 3.1 - 165"]}

Pachynolophus sp. (Fig. 10) MATERIAL. — AUM 199, right maxillary fragment with P3/-M3/; AUM 213, left M3/; AUM 1586, right maxillary fragment with (alv. P1/)-P2/-(M2/); AUM 1596, left fragment with P3/-P4/; AUM 1648, 1649, left P4/. AUM 162, left mandible fragment with M/2, (M/3); AUM 227, left M/3 (Pr. sudrei in Remy et al. 2016); AUM 323, symphysis with both /C and sockets of incisors; AUM 332, right DP/4; AUM 1557, right M/3; AUM 1599 left mandible fragment with (P/3)-(M/3); AUM 1600, right mandibular fragment with M/2-M/3; AUM 1602, left mandible fragment with M/2-M/3; AUM 1615, right mandible with P/4-M/3; AUM 1616, left fragment with M/3; AUM 1617, mandible with right /C-(alv. DP/1)- DP/2-M/3, and (alv. six I and left /C); AUM 1620, left mandible with DP/2-M/2-(M/3); AUM 1627 left mandible with M/2-M/3; AUM 1654, right M/3. DESCRIPTION The two featured upper cheek teeth series, AUM 199 and AUM 1586, are preserved in a very bad condition. AUM 199 which pertains to an old individual, is affected by a deep longitudinal fissure at the level of P3/-M2/ and the loss of ectoloph of M3/. The teeth of AUM 1586 are even more worn and molars partly broken. These specimens and other associated upper cheek teeth present rather conspicuous differences compared to Pachynolophus ruscassierensis n. sp. They are roughly 20% larger than average for most parameters. That would correspond to an estimated length of the row P2/-M3/ of at least 60 mm, and to an estimated weight of 28 kg (instead of 52 mm, 21 kg for Pa. ruscassierensis n. sp.) (Table 4; Appendix 8). As far as we can see, compared to Pa. ruscassierensis n. sp., the molars appear slightly more lophodont. The labial side of ectolophs is more slanted and indicates an IH index slightly lower. Thus the M3/ (AUM 213), although barely worn, has an IH of 0.40, near the lower variation limit of Pa. ruscassierensis n. sp. (Appendix 12). The metaloph of molars, more forwardly oriented, is directed to the distal side of paracone. The cingula are on the whole thinner and likely lower. The distal cingulum of M3/ is nevertheless fairly prominent, and it can give rise to a small hypostyle (AUM 213). The occlusal faces of P3/ and P4/ offer a more defined V shape. P3/ is more squared and has a wider lingual outline and a broader distal basin. In addition, the surface ratio of the premolar sector appears to be slightly lower than that of Pa. ruscassierensis n. sp. Thus, P4/ is somewhat smaller (SP 4/ SM3 = 49 instead of 52-59) and the ratio SP / SM (by combination of two specimens, AUM 199 and AUM 1586), could have reached only 38 to 42 instead of 44-49 (Appendix 21). P2/ is very unlike that of Pa. ruscassierensis n. sp. as it is almost rectangular and possesses two distinct labial cusps. Some mandibular fragments and lower teeth have been assigned to the same taxon on the basis of molar size. The crescents of the molars are rather sharp, not very rounded. The metastylid is not highly developed and poorly separated from metaconid. The ectocingulum is generally thin, variable in height (high on AUM 1599, lower on AUM 1617), and interrupted on cuspids except on AUM 1615. The P/4 (AUM 1599) is molariform, even if it bears only a small knob instead of a true entoconid. Its relative area is low compared to Pa. ruscassierensis n. sp. (Appendix 22). Despite P/3 (AUM 1599) is in a bad condition, we can see that the trigonid is long and tapers mesially. Its prominent protoconid overhangs a somewhat flattened crescent. The talonid is short and low, crossed by a weak ridge that ends in a small hypoconid. DP/4 is fully molariform. On AUM 332, the metastylid is clearly separated from metaconid but slightly lowered. The DP/3 outline slightly tapers mesially and the paralophid bears a tiny lingual accessory cuspid (AUM 1620). DP/2 is simple, with a prominent cusp, overhanging small mesial and distal knobs, with a very short talonid. DP/1 was bi-rooted. Other anatomical data The upper DPC is not preserved. On the mandible AUM 1617, the DPC (considered in that instance as the length /C-DP/2) measures 19.5 mm. With a teeth row length of about 63 mm, the DPC represents 31% of this value. But this specimen is a juvenile and is likely not representative of the adult condition. Due to its size, the mandibular fragment AUM 323 could perhaps be assigned to the same taxon. It shows a symphysal region not reaching alveoli of the P/1, but with both /C and the sockets of incisors. The preserved part of diastema is 24 mm long; assuming at least 6 mm for P/1 length (the DPC being the distance /C-P/2), with a tooth row length of 60 mm (estimation for AUM 199) to 63 mm (AUM 1617), this DPC (24 + 6) should have reached 48 to 50% of LRDJ. The mandibular body is more robust than that of Pa. ruscassierensis n. sp., high from 16 mm under the DPC, to 28 mm under M/3, with a minimal width of 12 to 16 mm at the DPC. On AUM 1617, a single foramen mentale is observed under DP/2. The vertical ramus is unknown. At maxillary level, the anterior opening of the infra-orbital foramen (FIO) is located above anterior half of P3/ (AUM 1586). COMMENTS The generic status of this assemblage needs some comments. It can be a priori assigned to Pachynolophus due to lack of mesostyle on upper molars, lack of hypocone or entoconid on premolars, rather sharp crescents on lower cheek teeth, long DPC. But, one might wonder whether these specimens should not rather refer to Propalaeotherium cf. gaudryi from Aumelas. Indeed, their size is identical, with variation limits overlapping almost exactly. Moreover, we know that some specimens lack mesostyle in Propalaeotherium gaudryi (Remy 2017). On the other hand several features clearly differentiate this cluster. First, the relative surface area of the premolar series seems smaller than in Pr. cf. gaudryi from Aumelas, (actually more alike than data observed in the true Pr. gaudryi !). Thus P4/ is rather small (SP 4/ SM3 = 49 instead of 50-61 in Pr. cf. gaudryi; SP 4/ SM = 18 instead of 19-22). Then, we speculate that the total surface of the premolars represents only 38 to 42% of the surface of the molars instead of 41 to 50% in Pr. cf. gaudryi (Appendices 9; 21 [caption]). Pachynolophus sp. from Aumelas P2/ P3/ P4/ M1/ M2/ M3/ L W L W L W L W D d L W D d L WD d N 1 1 3 3 5 5 2 1 1 2 1 1 1 1 2 2 2 1 mean 7.3 7.4 7.7 10.1 8.8 11.2 10.5 14.2 14.8 13.8 13.6 16.2 17.9 16.1 14. 16.5 17.2 16.3 variation – – 7.4-8.2 9.3-10.8 8.2-9.4 10.7- 10.1- – – 13.2- – – – – 14.0- 16.1- 17.1- – range 11.8 10.8 14.3 14.1 16.8 17.3 standard – – 0.436 0.764 0.537 0.527 – – – – – – – – – – – – deviation coeff. of – – 5.7 7.5 6.1 4.7 – – – – – – – – – – – – variation Comparison with Pa. ruscassierensis n. sp. upper series LP2-M3 LP2-P4 LM1-M3 PMI N 1 1 1 1 mean 60.6 24.3 (1) 36.3 67.1 P/2 P/3 P/4 M/1 M/2 M/3 L W1 W2 L W1 W2 L W1 W2 L W1 W2 L W1 W2 L W1 W2 W3 N 1 1 1 1 – – 2 2 2 4 4 4 8 7 8 9 9 9 9 mean 6.7 3.8 3.8 8.6 – – 9.0 6.6 6.6 9.9 7.3 7.7 11.8 8.3 8.3 17.2 8.7 7.7 5.9 variation – – – – – – 8.6- 6.5- 6.3- 9.6- 6.7- 7.2- 11.5- 7.9- 7.9- 16.2- 8.5- 7.1- 5.6- range 9.3 6.7 6.8 10.2 7.8 8.1 12.1 9.1 8.7 18.8 9.2 8.3 6.6 standard – – – – – – – – – 0.258 0.457 0.392 0.217 0.416 0.251 0.893 0.201 0.387 0.310 deviation coeff. of – – – – – – – – – 2.6 6.3 5.1 1.8 5.0 3.0 5.2 2.3 5.0 5.2 variation Comparison with Pa. ruscassierensis n. sp. DP/2 DP/3 DP/4 L W1 W2 L W1 W2 L W1 W2 N 2 2 2 2 2 2 3 3 3 mean 7.4 3.1 3.8 8.9 4.7 5.7 9.6 5.9 6.4 variation 7.3-7.4 3.1-3.1 3.7-3.9 8.4-9.3 4.6-4.7 5.6-5.7 9.1-10.3 5.5-6.2 5.9-6.8 range standard – – – – – – 0.643 0.361 0.458 deviation coeff. of – – – – – – 6.7 6.1 7.2 variation Some morphological differences are also conspicuous between the upper cheek teeth and those of Pr. cf. gaudryi from Aumelas as well as with those of Pr. gaudryi from the “Ageian fauna”. The parastyle of molars is a slightly less prominent. P3/ and P4/ have a more mesially shifted protocone with a broader distal basin. P2/ shows a more rectangular outline, with two more separated labial cusps. The lingual cingula are less developed. The associated mandibular specimens confirm this differentiation with respect to the lineage of Pr. gaudryi. Indeed, the crescents of the lobes of lower cheek teeth are less rounded and more acute. The DPC is likely longer than in Pr. gaudryi where it should not exceed 30 to 32% of LRDJ (Remy 2017). Conversely, we have seen that on the mandible AUM 323, it could have reached 50%. It seems that this set of specimens from Aumelas should not finally be brought close to a Propalaeotherium, and must rather be assigned to the genus Pachynolophus. Compared to Pa. ruscassierensis n. sp., conspicuous differences have been previously highlighted, particularly in size. The size difference with the genotypic species Pa. duvali, which is one of the smaller species of the genus, is even larger and around + 40%. Furthermore, despite some similarities that lead to bring the two forms closer together in a cladistic analysis (see below), the Aumelas specimens are quite distinct from this latter species by their P2/ even more square, their P3/ P4/ more transversely elongated. So, the Aumelas form can not be considered as affine to Pa. duvali. In fact, we are dealing with one of the largest Pachynolophus. Assuming that FSL-2977 could be a good representative of Pa. cesserasicus (see above), the specimens of Aumelas are about 15% larger for most parameters. Conversely, they are 15% smaller than the type and single specimen of Pa. cayluxi. Besides, compared to both species, the upper molars and mostly the P4/ of Aumelas are less bunodont, with ectolophs more flattened. All cingula are thinner and less continuous. P2/ is more quadrangular. Therefore, this Aumelas material probably represents an original new species, but it is too damaged and too poorly known to define a new taxon in the current state.

Propalaeotherium cf. gaudryi (Lemoine, 1878) (Fig. 7) MATERIAL. ��� AUM 47, right M3/; AUM 164, right maxillary fragment with M3/; AUM 168, right maxillary with canine and P1/ alveoli, P2/- P3/-(P4/-M2/)-M3/; AUM 192, right P4/; AUM 209, right maxillary fragment with M1/-M3/; AUM 1583, palate with right P1/-M2/ and left P2/-M3/; AUM 1584, left maxilla with P2/-M3/; AUM 1585, left maxilla with (P2/)-(P3/)-P4/-M1/; AUM 1587, right M2/-M3/; AUM 1590, left M3/; AUM 1592, left M2/; AUM 1593, left M3/; AUM 1594, right P4/; AUM 1595, left M2/; AUM 1658, 1659, left M3/. AUM 206, right mandible with (alv.P/1-alv.P/2)-P/3-M/3 (Pr. sudrei in Remy & al. 2016, fig. 3 E-F); AUM 236, right P/3; AUM 1560, right P/3; AUM 1561, right P/2; AUM 1601, right mandible with (P/4)-M/1- M/3; AUM 1603, right mandible with (P/3)-P/4-M/3; AUM 1604, right mandible fragment with M/1-M/2; AUM 1606, left mandible with P/4-M/3; AUM 1607, right (M/1)-M/2; AUM 1608, left M/2. DESCRIPTION We gather some maxillaries or maxillary fragments of Propalaeotherium, which display differences with Propalaeotherium sudrei and that present larger measurements (Table 2). Indeed the upper cheek teeth row is on average 13% longer (60- 62 mm instead of 54 mm), and the upper molar row is 16% longer (36-38 mm instead of 32 mm). All cheek teeth are on average 10% larger in linear measures. On lower cheek teeth, the length mean difference is of 8% (Appendices 16; 17). Upper teeth areas are about 30% larger (Appendix 10). Lower teeth areas (Appendix 11) show less mean size difference (14%). Most of these differences are significant (p: Pr. sudrei, and it may lack at least on M3/ (AUM 209, AUM 1583). On protoloph, the groove between protocone and paraconule varies in depth. It is deep on the M2/ and M3/ on AUM 209, but it is shallower on other specimens (e.g. AUM 1583). The metaloph, which lacks discernible metaconule, runs first toward the distal side of the paracone, and turns to reach the mesio-lingual side of the metacone. The lingual cingulum is well developed on these molars. Although thin and disrupted in front of the cusps, the cingulum is continuous on some M1/ (AUM 209) and M2/ (AUM 1592), but limited to the medivallum on the M3/ (AUM 168). The distal outline of M3/ is convex, with a strong distal cingulum, which eventually bears small knobs (hypostyle) (AUM 168, AUM 1583). The mean PMI is estimated to 70 (ranging from 68 to 71) and the mean SP / SM surface ratio is 44 (ranging from 41 to 50; Appendix 9). P4/ is transversely elongated (L/ W 0.73 on average). The labial cusps of P4/ are bunodont and close to each other, separated by a groove. The centrocrista is slightly notched and lacks mesostyle. The ectocingulum is continuous, not salient and its external outline is strongly concave. The styles are rather low and variably protruding. The protocone is mesio-distally centered. The paraconule is well defined even if the groove between protocone and paraconule is not deeply notched. The lingual outline is variable, narrow on AUM 192, wider on AUM 1583 with a large posterior basin. On AUM 192 and AUM 1594, there is a small metaconule connected to a curved postprotocrista, a somewhat starry feature. A cingulum encircles the whole internal part of the tooth on most specimens (AUM 192 and AUM 1594), but it is interrupted at the protocone on AUM 1592, AUM 1584, and AUM 168 (very worn). P3/ offers a similar shape but is less transversely elongated; AUM 1584 is almost quadratic. The bunodont labial cusps are slightly tighter than on P4/. They display a labial continuous and concave cingulum. The parastyle is stronger and protrudes outward and forward. It appears weaker on AUM 168 with a metastyle as marked as parastyle. The lingual shape is wider than on P4/. It is even much enlarged on AUM 1584, which is nearly rectangular, with a slightly forwardly shifted protocone. Conversely on AUM 168, the internal contour remains narrow and the protocone is centered. The protoloph is not deeply notched and the paraconule is almost indistinct on AUM 1584 (more individualized on AUM 168). We note the presence of a postprotocrista that lacks a well-defined metaconule. Conversely, the metaconule is well marked on AUM 168, it is low and sinuous on AUM 1584. The lingual cingulum is always interrupted facing the protocone. P2/ seems rather variable. On AUM 168 and AUM 1584, it is a triangular tooth, barely enlarged transversely and tapering forward. On the distal crest of the prominent paracone, which is remote forward, we note the presence of a small but rather individualized low metacone. The ectocingulum is continuous, rather weak, and less thick than on P3/ and P4/. Likewise the styles are weak. The internal part of the tooth is surrounded by a continuous cingulum. A rise of this cingulum, at the widest level of the tooth, evokes a small protocone. On AUM 1584, a tiny knob is present at the place of the metaconule. AUM 1583 shows on the right P2/ a structure according to this description, but the left P2/ is transversely broader, with a well marked protocone and a rather wide posterior basin. P1/, partly preserved on the right side on AUM 1583, is a simple elongated tooth, surrounded by a circular cingulum, its prominent cusp is barely shifted oralwards. The two alveoli of P1/ are also to be seen on AUM 168. On both specimens, there was not any diastema between P1/ and P2/. Ten lower jaw fragments or isolated teeth are related to this taxon (Fig. 7). The teeth are first characterized by their dimensions larger than those of Pr. sudrei (see above). Mor- phologically, this material offers little information to differentiate the taxon compared to other Propalaeotherium, because of the weak characterization of the lower cheek teeth and of individual variations. One can only observe that the crescents of the molars are fairly rounded, and their metaconid are generally well splitted. The labial cristid of the M/3 hypoconulid is connected halfway to the hypolophid. The ectocingulum is quite variably developed. Moreover, P/4 is rather bulbous; its talonid, a bit wider than on Pr. sudrei, is slightly lower than the trigonid; it does not show any hypolophid, but a tiny entoconid is present. P/3 is narrowed mesially and the crescent of the trigonid is very flat. The anterior cingulum lacks paraconid. The protoconid is linked to the metaconid through a very oblique protolophid. The talonid is short and the metalophid is low and oblique disto-labially, free of a well-developed hypoconid. Anterior teeth are not known. Only few observations are available concerning the skull morphology. The alveolus of a rather large and mesio-distally elongated canine is preserved on AUM 168, which was likely pertaining to a male. This allows evaluating relative length of the DPC. It was 21 mm long with a LRDJ of 62 mm, and the % DPC is estimated at 33.9 (Appendix 20A). The obliquity of the nasal opening edge suggests that the notch did not likely exceed the level of P1/. The anterior opening of the infraorbital canal (FIO) is open 9 mm above the alveolar margin, its distal edge is very rostrally located, above the limit P2/-P3/. The morphology of the mandible is also only partly known. The mandibular body is not very high (26 mm under M/3; AUM 1601, AUM 1603) and it seems not to be much lowered under the premolar row. A mental foramen opens under the limit P/3-P/4, and a smaller one under P/1 (AUM 206). The angular process is broad and is not ventrally protruding. The vertical ramus seems to have been high (AUM 1606). COMMENTS As already noticed, this material is significantly larger than that of Pr. sudrei. It is also greater than Pr. voigti (oUK to MK) with differences averaging about +8% in linear measures and about +24% in surfaces (p: Pr. hassiacum and Pr. isselanum. As a result, their measures are only compatible with Pr. gaudryi from the Paris Basin or with the specimens of the Geiseltal uUK usually referred to Pr. voigti. The specimens from Rouzilhac (molassic beds of Issel, Aude, France), recently assigned to the taxon (Godinot et al. 2018) also seem to be about the same size. Actually, with the available material of Aumelas, differences of upper cheek teeth size relative to Pr. gaudryi are negligible. Likewise, as regards lower cheek teeth, the dimensions fall within variation ranges of that taxon (Appendices 16; 17). Great morphological similarities are also observed at Aumelas with Pr. gaudryi. Like in Pr. gaudryi, a mesostyle is not always present on upper molars. The degree of brachyodonty is identical, more marked than on Pr. sudrei (Fig. 4). The enamel appears rather thick. Besides, we find as in Pr. gaudryi the great development of the parastyle of upper molars, the usually moderate splitting of the protoloph. The shape of the premolars P3/ and P4/ is similar, they are more transversally elongated than on Pr. sudrei. Moreover we may observe on P4/ a metaconule distally connected to the postprotocrista as on some specimens of Pr. gaudryi (NMB TS-83). Like in Pr. gaudryi, P2/ bears two distinct labial cusps. Its shape is rather variable, from triangular, anteriorly tapering, to almost quadratic. The material of the Geiseltal uUK up to now referred to as ��� Pr. voigti ��� (see above), which presents great similarities with these specimens, might also be close to Pr. gaudryi. Nevertheless, the Aumelas material differs from Pr. gaudryi by several features that prevent a complete assimilation to this species, in the current state of knowledge. First, the relative surface of upper premolar area seems slightly greater (although the difference be not significant, failing sufficient documentation, and due to the variability of P2/). Thus the SP 4/ SM3 ratio reaches 54 (50 to 61) instead of 51 (49 to 54) for Pr. gaudryi). The material of Rouzilhac presents values close to those of Aumelas: the same ratio is 56 on the maxillary RZ-221 (Godinot et al. 2018: fig. 40-a). Then the lingual cingula are slightly less marked than with typical Pr. gaudryi, notably on premolars, and finally there is no P1/-P2/ diastema. These observations would attest to the slightly more progressive nature of the form of Aumelas (as well as that of Rouzilhac material, also recognized by the authors of the monograph) compared with Propalaeotherium gaudryi from the Paris basin. urn:lsid:zoobank.org:act: F10B45D3-0CC9-4CD4-8E38-0C568BBC7038 Finally, the Aumelas material could be closer to the taxon of Rouzilhac than to that latter. However, the name of Propalaeotherium cf. gaudryi is retained because of the meager fossil register, Published as part of Remy, Jean A., Krasovec, Gabriel, Lopez, ��ric, Marandat, Bernard & Lihoreau, Fabrice, 2019, The Palaeotheriidae (Equoidea, Perissodactyla, Mammalia) from the Eocene fauna of Aumelas (H��rault department, France), pp. 525-585 in Geodiversitas 41 (13) on pages 534-537, DOI: 10.5252/geodiversitas2019v41a13, http://zenodo.org/record/3699849, {"references":["REMY J. A., KRASOVEC G. & MARANDAT B. 2016. - A new species of Propalaeotherium (Palaeotheriidae, Perissodactyla, Mammalia) from the Middle Eocene locality of Aumelas (Herault, France). Palaeovertebrata 40 (2): 1 - 8, supp. data 1 - 6. https: // doi. org / 10.18563 / pv. 40.2. e 1","GODINOT M., LABARRERE H. - P., ERFURT J., FRANZEN J. L., LANGE- BADRE B., DE LAPPARENT DE BROIN F. & VIDALENC D. 2018. - Un nouveau gisement a vertebres eocenes, Rouzilhac (MP 10 - 11), dans la serie molassique d'Issel (Aude, France). Revue de Paleobiologie 37 (1): 141 - 333."]}

Genus Propalaeotherium Gervais, 1849 EMENDED DIAGNOSIS OF GENUS (according to Remy et al. 2016). ��� Small to large equoids with estimated skull length from 120 to about 250 millimeters; dental formula: 3.1.4.3/3.1.4.3; brachylophodont dentition; upper molars with more or less pronounced mesostyle; upper premolars non-molariform, lacking hypocone; mesostyle on P3-4/ and entoconid on P/3-4 only present in youngest species; lower cheek teeth without paraconid; lower molars with rounded crescentic lobes and twinned prominent rnetaconid; lingual cingula on upper molars, usually weak or absent; lower cheek teeth with more or less developed labial cingula, but with weak or absent lingual cingula; rather short postcanine diastema. Propalaeotherium differs from Eurohippus by a wider skull and narrower ramus with regard to its height. TYPE SPECIES. ��� Propalaeotherium isselanum (Cuvier, 1824). INCLUDED SPECIES. ��� Pr. argentonicum Gervais, 1849, Pr. gaudryi (Lemoine, 1878) (synonym of Propachynolophus gaudryi Lemoine, 1878; see Remy 2017), Pr. hassiacum Haupt, 1925, Pr. helveticum Savage, Russell, Louis, 1965, Pr. voigti Matthes, 1977., Published as part of Remy, Jean A., Krasovec, Gabriel, Lopez, ��ric, Marandat, Bernard & Lihoreau, Fabrice, 2019, The Palaeotheriidae (Equoidea, Perissodactyla, Mammalia) from the Eocene fauna of Aumelas (H��rault department, France), pp. 525-585 in Geodiversitas 41 (13) on page 528, DOI: 10.5252/geodiversitas2019v41a13, http://zenodo.org/record/3699849, {"references":["REMY J. A., KRASOVEC G. & MARANDAT B. 2016. - A new species of Propalaeotherium (Palaeotheriidae, Perissodactyla, Mammalia) from the Middle Eocene locality of Aumelas (Herault, France). Palaeovertebrata 40 (2): 1 - 8, supp. data 1 - 6. https: // doi. org / 10.18563 / pv. 40.2. e 1","REMY J. A. 2017. - Critical comments on the genus Propachynolophus Lemoine, 1891 (Mammalia, Perissodactyla, Equoidea). Palaeovertebrata 41 (1) - e 3: 1 - 18. https: // doi. org / 10.18563 / pv. 41.1. e 3","SAVAGE D. E., RUSSELL D. E. & LOUIS P. 1965. - European Eocene Equidae (Perissodactyla). University of California Publications in Geological Sciences, vol. 56, 94 p."]}

Apoptosis has been considered as merely required for the removal of supernumerary cells or larval structures by dismantling cells with a characteristic and conserved set of morphological and biochemical features (Destructive Function of Apoptosis, DFA). Accumulating evidences show how apoptotic cells can trigger and modulate other cell behaviors (migration) or cell fates (proliferation, survival, differentiation) during very different morphogenetic events in numbers of animals. These studies led us to define a novel morphogenetic role of apoptosis, hereafter referred as the Constructive Function of Apoptosis (CFA). To investigate the CFA and its evolution in animals, I initiated characterization of CFA during metamorphosis of two distantly related species with a key phylogenetic position, the cnidarian Clytia hemisphaerica, and the tunicate, Ciona intestinalis. In C. hemisphaerica, I have identified and characterized endodermic and ectodermic apoptosis in planula larva. This apoptosis occurred in the larva at the same area and at the same time with the proliferation and differentiation of i-cells and nematocytes migration. All together, these results arguing in favor of planula metamorphosis as an excellent model to study CFA. In C. intestinalis, I have demonstrated that primordial germ cells migration is due to CFA during the tail regression process, leading to the molecular characterization of CFA in this model.; L'apoptose est une mort cellulaire très bien caractérisée d’un point de vue morphologique et biochimique mais dont le rôle morphogénétique a longtemps été restreint à une destruction des structures transitoires ou surnuméraires (Fonction Destructrice de l’Apoptose, FDA). Plus récemment une capacité des cellules apoptotiques à modifier le comportement (migration) ou le destin (prolifération, différenciation, survie) des cellules voisines a été mise en en évidence dans des modèles expérimentaux et des contextes morphogénétiques très divers. Nous avons décidé de regrouper et nommer ces capacités au sein d'une même fonction morphogénétique, la Fonction Constructrice de l'Apoptose (FCA). Afin de mieux comprendre le fonctionnement et l’évolution de la FCA, j'ai utilisé le cadre morphogénétique de la métamorphose, caractérisée par la présence simultanée d’apoptose et de l’ensemble des comportements et destins cellulaires, chez deux organismes éloignés phylogénétiquement, le cnidaire Clytia hemisphaerica et le tunicier Ciona intestinalis. Chez C. hemisphaerica, j’ai identifié et caractérisé dans la larve planula en métamorphose de l’apoptose ectodermique et endodermique, la prolifération et la différenciation des i-cells en nématocytes et la migration de ces derniers. Ces résultats confortent l’utilisation de ce modèle pour étudier la FCA. Chez C. intestinalis, j'ai démontré que la migration des Cellules Germinales Primordiales (PGC) est un exemple de FCA, permettant ainsi une caractérisation moléculaire de cette dernière.

Apoptosis has been considered as merely required for the removal of supernumerary cells or larval structures by dismantling cells with a characteristic and conserved set of morphological and biochemical features (Destructive Function of Apoptosis, DFA). Accumulating evidences show how apoptotic cells can trigger and modulate other cell behaviors (migration) or cell fates (proliferation, survival, differentiation) during very different morphogenetic events in numbers of animals. These studies led us to define a novel morphogenetic role of apoptosis, hereafter referred as the Constructive Function of Apoptosis (CFA). To investigate the CFA and its evolution in animals, I initiated characterization of CFA during metamorphosis of two distantly related species with a key phylogenetic position, the cnidarian Clytia hemisphaerica, and the tunicate, Ciona intestinalis. In C. hemisphaerica, I have identified and characterized endodermic and ectodermic apoptosis in planula larva. This apoptosis occurred in the larva at the same area and at the same time with the proliferation and differentiation of i-cells and nematocytes migration. All together, these results arguing in favor of planula metamorphosis as an excellent model to study CFA. In C. intestinalis, I have demonstrated that primordial germ cells migration is due to CFA during the tail regression process, leading to the molecular characterization of CFA in this model.; L'apoptose est une mort cellulaire très bien caractérisée d’un point de vue morphologique et biochimique mais dont le rôle morphogénétique a longtemps été restreint à une destruction des structures transitoires ou surnuméraires (Fonction Destructrice de l’Apoptose, FDA). Plus récemment une capacité des cellules apoptotiques à modifier le comportement (migration) ou le destin (prolifération, différenciation, survie) des cellules voisines a été mise en en évidence dans des modèles expérimentaux et des contextes morphogénétiques très divers. Nous avons décidé de regrouper et nommer ces capacités au sein d'une même fonction morphogénétique, la Fonction Constructrice de l'Apoptose (FCA). Afin de mieux comprendre le fonctionnement et l’évolution de la FCA, j'ai utilisé le cadre morphogénétique de la métamorphose, caractérisée par la présence simultanée d’apoptose et de l’ensemble des comportements et destins cellulaires, chez deux organismes éloignés phylogénétiquement, le cnidaire Clytia hemisphaerica et le tunicier Ciona intestinalis. Chez C. hemisphaerica, j’ai identifié et caractérisé dans la larve planula en métamorphose de l’apoptose ectodermique et endodermique, la prolifération et la différenciation des i-cells en nématocytes et la migration de ces derniers. Ces résultats confortent l’utilisation de ce modèle pour étudier la FCA. Chez C. intestinalis, j'ai démontré que la migration des Cellules Germinales Primordiales (PGC) est un exemple de FCA, permettant ainsi une caractérisation moléculaire de cette dernière.