Exceptional soft tissues preservation in a mummified frog-eating Eocene salamander

Fossils are almost always represented by hard tissues but we present here the exceptional case of a three-dimensionally preserved specimen that was ‘mummified’ (likely between 40 and 34 million years ago) in a terrestrial karstic environment. This fossil is the incomplete body of a salamander, Phosphotriton sigei, whose skeleton and external morphology are well preserved, as revealed by phase-contrast synchrotron X-ray microtomography. In addition, internal structures composed of soft tissues preserved in three dimensions are now identified: a lung, the spinal cord, a lumbosacral plexus, the digestive tract, muscles and urogenital organs that may be cloacal glands. These are among the oldest known cases of three-dimensional preservation of these organs in vertebrates and shed light on the ecology of this salamander. Indeed, the digestive tract contains remains of a frog, which represents the only known case of an extinct salamander that fed on a frog, an extremely rare type of predation in extant salamanders. These new data improve our scarce knowledge on soft tissue anatomy of early urodeles and should prove useful for future biologists and palaeontologists working on urodele evolutionary biology. We also suggest that the presence of bat guano and carcasses represented a close source of phosphorus, favouring preservation of soft tissues. Bone microanatomy indicates that P. sigei was likely amphibious or terrestrial, and was probably not neotenic

Rhinocerotidae from the early middle miocene locality Gračanica (Bugojno basin, Bosnia-Herzegovina)

The early middle Miocene (European Land Mammal Zone MN5) locality Gračanica (Bugojno Basin, Bosnia-Herzegovina) has yielded numerous well-preserved dental remains of four Rhinocerotidae species: Brachypotherium brachypus, Lartetotherium sansaniense, Plesiaceratherium balkanicum sp. nov. and Hispanotherium cf. matritense. This rhinocerotid assemblage is typical of the Orleanian European Land Mammal Age and indicates a mesic woodland with diverse habitats from swampy forest to drier and more open environment

Early Agenian rhinocerotids from Wischberg (Canton Bern, Switzerland) and clarification of the systematics of the genus Diaceratherium

Background: Wischberg is a Swiss locality in Bern Canton which has yielded numerous vertebrates remains from the earliest Miocene (= MN1). It has a very rich faunal diversity, one of the richest in Switzerland for this age. Among all the mammals reported in the original faunal list 70 years ago, three rhinocerotid species were identified. The material consists of two fragmentary skulls, cranial fragments, several mandibles, teeth and postcranial bones, in a rather good state of preservation.Results: After reexamination of the material from this locality (curated in three different Swiss museums) and comparison with holotype specimens, we show that all rhinocerotid specimens from Wischberg can be referred to two species only. Most of the material can be attributed to the large-sized teleoceratine Diaceratherium lemanense, while only a few specimens, including a skull and mandible, belong to the much smaller sized Pleuroceros pleuroceros. We describe and illustrate for the first time most of these fossil remains. However, the systematics of the genus Diaceratherium is currently controversial, and based on our new observations we consider seven species as valid, though a large-scale phylogenetic study should be done in the future to resolve it. The rhinocerotid association found in Wischberg is nonetheless typical of the MN1 biozone, which results from a faunal renewal occurring just before the end of the Oligocene

New data on Amynodontidae (Mammalia, Perissodactyla) from Eastern Europe: Phylogenetic and palaeobiogeographic implications around the Eocene-Oligocene transition

Amynodontidae is a family of Rhinocerotoidea (Mammalia, Perissodactyla) known from the late Early Eocene to the latest Oligocene, in North America and Eurasia. European Amynodontidae are very rare, and all remains belong almost exclusively to a single post—Grande Coupure genus from the Oligocene, Cadurcotherium. The “Grande Coupure” defines an extinctions and dispersal-generated originations event in Europe that is nearly contemporaneous with the Eocene-Oligocene transition. Perissodactyls are one of the major groups affected by this event: Palaeotheriidae went almost extinct during this crisis, whereas Rhinocerotidae appeared for the first time in Europe. Study of fossiliferous Eastern-European localities from this age is crucial for the understanding of this crisis. We report here three new localities of Amynodontidae in Eastern Europe. Two of them are dated from the Eocene (Morlaca, Romania; Dorog, Hungary), whereas the other is either Late Eocene or Early Oligocene (Dobârca, Romania). The skull from this latter locality belongs unexpectedly to the same individual as a previously described mandible attributed to “Cadurcodon” zimborensis. As a result, this specimen can be allocated to its proper locality, Dobârca, and is assigned to a new genus, Sellamynodon gen. nov. It is characterised by an extraordinary growth of the nuchal crest, a unique character among amynodontids. Along with this remarkable material from Dobârca, two specimens from another Romanian locality, Morlaca, have been recently discovered and are dated from the Late Eocene. They belong, as well as new material from Dorog (Middle Eocene, Hungary), to the genus Amynodontopsis, also found in North America. The new Hungarian material represents the earliest occurrence of Amynodontidae in Europe. New phylogenetic hypotheses of Rhinocerotoidea are proposed, including the new material presented here, and show that Amynodontidae may be closer to the polyphyletic family ʽHyracodontidaeʼ than to Rhinocerotidae. Amynodontidae, with their deep preorbital fossa and extremely reduced premolars, display in fact a very derived condition, compared to rhinocerotids

3D models related to the publication: New material of Epiaceratherium and a new species of Mesaceratherium clear up the phylogeny of the early Rhinocerotidae (Perissodactyla)

The present 3D Dataset contains two 3D models described in Tissier et al. (https://doi.org/10.1098/rsos.200633): the only known complete mandible of the early-branching rhinocerotoid Epiaceratherium magnum Uhlig, 1999, and a hypothetical reconstruction of the complete archetypic skull of Epiaceratherium Heissig, 1969, created by merging three cranial parts from three distinct Epiaceratherium species

Diaceratherium lemanense

Diaceratherium lemanense (Pomel, 1853) (2 specimens) FRANCE – Gannat • 1 hand; MNHN-LIM-598 • 1 astragalus; NMB-Gn-158.Published as part of Tissier, Jérémy, Antoine, Pierre-Olivier & Becker, Damien, 2021, New species, revision, and phylogeny of Ronzotherium Aymard, 1854 (Perissodactyla, Rhinocerotidae), pp. 1-80 in European Journal of Taxonomy 753 on page 80, DOI: 10.5852/ejt.2021.753.1389, http://zenodo.org/record/494587

New species, revision, and phylogeny of Ronzotherium Aymard, 1854 (Perissodactyla, Rhinocerotidae)

International audienceRonzotherium is one of the earliest Rhinocerotidae in Europe, which first appeared just afterthe Eocene/Oligocene transition (Grande Coupure), and became extinct at the end of the Oligocene. It is a large-sized rhinocerotid, with a special position in the phylogeny of this group, as being one of the earliest-branching true Rhinocerotidae. However, its intra-generic systematics has never been tested through computational phylogenetic methods and it is basically unknown. Its taxonomical history has gone through numerous complications, and thus we aim to provide here a complete revision of this genus, through phylogenetic methods. After a re-examination of all type specimens (five supposed species) as well as of most well-preserved specimens from all over Europe and ranging through the complete Oligocene epoch, we performed a parsimony analysis to test the position of some problematic specimens. According to our results, five species can be distinguished, Ronzotherium velaunum (type species), R. filholi, R. elongatum and R. romani as well as a new species: R. heissigi sp. nov. We also drastically re-interpret its anatomy and show that the ‘short-limbed’ “Diaceratherium” massiliae, described from Southern France, can be considered as a junior synonym of R. romani. Finally, we exclude the Asian species “Ronzotherium” orientale and “Ronzotherium” brevirostre from Ronzotherium and we consider R. kochi as a junior synonym of R. filholi

Ronzotherium elongatum Heissig 1969

Ronzotherium elongatum Heissig, 1969 Figs 8–10 Ronzotherium filholi elongatum Heissig, 1969: 46–55, 68, 71, 116, 119, fig. 18d (from Pernes and Kleinblauen). Rhinoceros filholi – Jenny 1905: 125. Aceratherium filholi – Jenny 1905: 125. — Roman 1910: 1559 (from Pernes and Kleinblauen); 1912a: 17, 27, 45–50, 57–58, figs 14.1, 15, 18, pl. V figs 1–2 (from Pernes and Kleinblauen); 1912b: 360– 364, fig. 2. — Stehlin 1914: 185 (from Kleinblauen). — Gignoux 1928: 148, 151, fig. 3 (from Pernes and Kleinblauen). Praeaceratherium filholi – Spillmann 1969: figs 11, 13, 16. Ronzotherium filholi – Brunet 1979: 105, table 2 (from Pernes and Kleinblauen). — Becker 2003: 212–213, 230–231, 234, 256, pl. II fig. a–d (from Kleinblauen); 2009: 490, 493–495, fig. 4h–l, table 1 (from Kleinblauen). — Ménouret & Guérin 2009: 296 (from Pernes and Kleinblauen). Non Ronzotherium filholi elongatum – Heissig 1969: 46–55, figs 16–17, 18a–c, 19 (from Villebramar, Bumbach, Montans, Cournon). Historical diagnosis From Heissig (1969), translated by the authors: “A subspecies of Ronzotherium filholi with the following characteristics: corpus mandibulae low, very slender, fossa masseterica deeply concave, foramen mandibulae at about the level of the teeth neck, strongly enlarged, symphysis long, flat forward; i2 still shearing towards I1, i1 present; angle of jaw branches very pointed; upper molars elongated with very broad medisinus, extremely short post-fossette and strong lingual cingulum; upper P3 and P4 premolariform to semimolariform, P2 molariform, protocone and hypocone widely separated, all upper premolars strongly widened, inside slightly rounded, metaloph curved and S-shaped, often with complicated folds, hypostyle missing; lower molars with strong labial cingulum and relatively long anterolingual cingulum, relatively long, narrow and conspicuously low, talonid pit unclear or notched; lower premolars, especially p3 often lengthened to the front, protoconid fold strong, metalophid strongly backwards, labial cingulum strong, p2 strongly narrowed, p1 single-rooted.” However, this diagnosis is not only based on the type material, but also on referred material from other localities, such as Villebramar or Bumbach that we refer to other species. We thus propose an emended diagnosis. Emended diagnosis The paraoccipital process is poorly developed. The roots of the upper cheek teeth are lingually fused, P2 is molariform with a lingual bridge connecting the protocone and hypocone, the protocone and hypocone form a lingual wall on P3 and P4, with a well-marked lingual groove above the cingulum, especially on P4. Upper premolars usually bear a simple crochet, the protocone is slightly constricted, the metaloph curved and S-shaped and the hypostyle missing. The protocone is usually constricted on upper molars and the lingual cingulum is strong and continuous, except under the hypocone of M1–2 and the protocone of M2. The labial cingulum of the lower molars is always present and continuous. Differs from Ronzotherium filholi by the presence of a processus postorbitalis on the zygomatic arch and by its poorly developed processus paraoccipitalis. Type material Holotype FRANCE • two-parts well preserved skull with almost complete cheek teeth rows, the two parts are joined together by plaster, which does not reflect the original morphology; Vaucluse, Pernes-les- Fontaines; probably MP23; FSL-9601. Additional material No other material is known from this locality. Type horizon and locality Pernes (= Pernes-les-Fontaines, Vaucluse, France), probably dated from MP23. The ‘sands and green sandstones of the Valette-de-Pernes’ in which this skull was found, have been dated from MP 23 in Murs, another locality 20 km from Pernes. Stratigraphical distribution Early Oligocene. Geographical distribution France: Pernes. Switzerland: Kleinblauen. Description SKULL. The skull was originally described by Roman (1912a, 1912b), who attributed it to Ronzotherium filholi. It is heavily reconstructed in plaster, especially the frontals and parietals, but it is nonetheless possible to identify the original bony material (Figs 8–9). The nasals are very fragmentary, the anterior part is broken. The lateral apophysis is not preserved. The infraorbital foramen opens above P4. The posterior border of the nasal incision is above P3 and the anterior border of the orbit is above the middle of M1. The lachrymal process is well developed and there is a large postorbital process of the frontals above the orbit. Only the anterior parts of the jugal bones are preserved, and the anterior base of the zygomatic arch is high above the teeth neck. The postorbital process of the zygomatic arch is large and on the jugal. The squamosals are not preserved. The dorsal profile of the skull is difficult to interpret, because of the heavy reconstruction, yet it was probably concave, though not as much as suggested by the reconstruction. The area between the temporal and nuchal crests is very concave. The external auditory pseudomeatus is ventrally open, between the postglenoid and posttympanic apophyses. The nuchal tubercle is well-developed. From the preserved part of the parietal bone, we can observe a wide parietal crest. The occipital crest is concave. In ventral view, the anterior part of the zygomatic arch does not strongly diverge from the maxilla. The vomer is badly preserved. The articular tubercle of the squamosal is smooth and tranversally straight. The postglenoid apophysis is rounded and convex anteriorly, and anteroposteriorly elongated. The foramen nervi hypoglossi is in the middle of the condylar fossa. There is a strong and high sagittal crest on the basilar process of the basioccipital. In occipital view, the paraoccipital and posttympanic processes are fused. The posttympanic process is well-developed and the paraoccipital process is partly broken. The foramen magnum is circular. There is neither a median crest nor a medial truncation on the occipital condyles. UPPER CHEEK TEETH. No anterior teeth are preserved on the skull, only the cheek teeth (Figs 8B–C, 9B–C, 10C–D). The three molars are well preserved on both sides, but the ectolophs of P3–4 are missing, whereas P2 is well preserved and P1 is absent on both sides. There is, however, a single broken root still preserved on the left side which means that this tooth was present in the juvenile at least. The premolar series is short compared to the molar series (LP3–4/LM1–3 = 0.48). There are no enamel folds and the cement is absent. The crown of the cheek teeth is low. The labial cingulum is strong and continuous on P2, but the ectolophs are broken on P3–4 so we cannot determine whether it was present or absent. The lingual cingulum is very strong and continuous on P2–4 and is rippled in lingual view, especially on P4. There is a short but well-defined crochet on P3–4. It is simple, directed towards the protocone and completely missing on P2. The metaloph is not constricted and the postfossette is narrow. The antecrochet is always absent. The protocone and hypocone of P2 are connected by a low bridge and are rather equal in size. The protoloph of P2 is directed slightly postero-lingually while the metaloph is S-shaped and transverse. They are both joining the ectoloph. The paracone and metacone folds of P2 are present and wide. The medifossette is always absent on premolars and the protocone is never constricted. The protocone and hypocone of P3–4 form a lingual wall, and a lingual groove is present. The metaloph of P3–4 is S-shaped and directed postero-lingually. The protoloph and metaloph of P3–4 are connected to the ectoloph. The labial cingulum is strong under the metastyle of M1–2 and the parastyle of M1 but is absent otherwise. The lingual cingulum is also strong and almost completely continuous on all upper molars. It is only fainted under the hypocone of M1 and the protocone of M2. The anterior and posterior cingulum are continuous. The antecrochet is present, but poorly defined and only appears effectively on the protoloph with very strong wear. The crochet, crista and medifossette are always absent on upper molars. The protocone is always weakly constricted. The paracone fold is strong and there is neither a metacone fold nor a mesostyle. The metastyle and metaloph are long and the posterior part of the ectoloph is straight. The hypocone is never constricted and the anterior groove of the metaloph is very shallow or absent. The postfossette is short, but deep, below the posterior cingulum. The ectoloph and metaloph of M3 are completely fused, and the posterior groove is very shallow. It is quadrangular in occlusal view. The protoloph is transverse. There is a small crest in the median valley of the left M3, that seem to have been broken on the right one. It may be caused by individual variation and is completely absent on other molars. Remark This species is the most recently one erected, though it was originally considered a subspecies of R. filholi. Brunet (1979) and subsequent authors considered it as a junior synonym of R. filholi. Based on our comparative work and our phylogeny, we consider it as a valid species.Published as part of Tissier, Jérémy, Antoine, Pierre-Olivier & Becker, Damien, 2021, New species, revision, and phylogeny of Ronzotherium Aymard, 1854 (Perissodactyla, Rhinocerotidae), pp. 1-80 in European Journal of Taxonomy 753 on pages 22-27, DOI: 10.5852/ejt.2021.753.1389, http://zenodo.org/record/494587

Diaceratherium aginense

Diaceratherium aginense (Répelin, 1917) (7 specimens) FRANCE – Laugnac • 1 scaphoid; MHNM.1996.17.94 • 1 lunate; MHNM.1996.17.21 • 1 pyramidal; MHNM.1996.17.20 • 1 unciform; MHNM.1996.17.98 • 3 astragali; MHNM.1996.17.41, MHNM.1996.17..55, MHNM.1996.17..77.Published as part of Tissier, Jérémy, Antoine, Pierre-Olivier & Becker, Damien, 2021, New species, revision, and phylogeny of Ronzotherium Aymard, 1854 (Perissodactyla, Rhinocerotidae), pp. 1-80 in European Journal of Taxonomy 753 on page 80, DOI: 10.5852/ejt.2021.753.1389, http://zenodo.org/record/494587

Ronzotherium Aymard 1854

Genus Ronzotherium Aymard, 1854 Type species Ronzotherium velaunum (Aymard in Pictet, 1853) Other species Ronzotherium filholi (Osborn, 1900); Ronzotherium romani Kretzoi, 1940; Ronzotherium elongatum Heissig, 1969; Ronzotherium heissigi sp. nov. Emended diagnosis These are large-sized hornless rhinocerotoids with two pointed upper incisors (I1 and I2) but only one large tusk-shaped lower incisor (i2) and without canines. The crown of the i1 is reduced. The dorsal profile of the skull is concave. The nasal incision is short and opening above P1–3. The anterior border of the orbit is above the molars and the infraorbital foramen is above P3–4. The processus posttympanicus and paraoccipitalis are fused at their base. The upper premolars are not molarised and the hypocone is always connected or completely fused to the protocone on P3–4. The upper molars are simple, with poorly developed crochet and antecrochet and the crista is always absent. The posterior part of the ectoloph of the upper molars is straight. The M3 is quadrangular in occlusal view. The ectoloph and metaloph are fused into an ectometaloph on M3, and there is no metastyle, but a posterior groove remains. The entoconid is very poorly developed on the lower premolars, or completely absent, and the opening of the posterior valley is wide and U-shaped. The lower d1 is usually absent. The ectolophid groove of the lower molars is developed until the neck. The distal articulation of the pyramidal for the lunate is symmetrical in medial view, the indentation on the medial side of the magnum is absent and the posterior tuberosity of the magnum is short. The collum tali of the astragalus is high. Stratigraphical distribution Late Eocene (?) to latest Oligocene. Geographical distribution Europe.Published as part of Tissier, Jérémy, Antoine, Pierre-Olivier & Becker, Damien, 2021, New species, revision, and phylogeny of Ronzotherium Aymard, 1854 (Perissodactyla, Rhinocerotidae), pp. 1-80 in European Journal of Taxonomy 753 on page 10, DOI: 10.5852/ejt.2021.753.1389, http://zenodo.org/record/494587