Judit Marigó

Astragalar and calcaneal morphology of the middle Eocene primate Anchomomys frontanyensis (Anchomomyini): Implications for early primate evolution

Astragali and calcanei of Anchomomys frontanyensis, a small adapiform from the middle Eocene of Sant Jaume de Frontanyà (Southern Pyrenean basins, northeastern Spain) are described in detail. Though these bones have been known for some time, they have never been carefully analyzed in a context that is comprehensively comparative, quantitative, considers sample variation (astragalus n = 4; calcaneus n = 16), and assesses the phylogenetic significance of the material in an explicit cladistic context, as we do here. Though these bones are isolated, regression analyses provide the first formal statistical support for attribution to A. frontanyensis. The astragalus presents features similar to those of the small stem strepsirrhine Djebelemur from the middle Eocene of Tunisia, while the calcaneus more closely resembles those of the basal omomyiform Teilhardina. The new phylogenetic analyses that include Anchomomys postcranial and dental data recover anchomomyins outside of the adapiform clade, and closer to djebelemurids, azibiids, and crown strepsirrhines. The small size of A. frontanyensis allows comparison of similarly small adapiforms and omomyiforms (haplorhines) such that observed variation has more straightforward implications for function. Previous studies have demonstrated that distal calcaneal elongation is reflective of leaping proclivity when effects of body mass are appropriately accounted for; in this context, A. frontanyensis has calcaneal elongation suggesting a higher degree of leaping specialization than other adapiforms and even some early omomyiforms. Moreover, comparison to a similarly-sized early adapiform from India, Marcgodinotius (which shows no calcaneal elongation) confirms that high distal calcaneal elongation in A. frontanyensis cannot be simply explained by allometric effects of small size compared to larger adapiform taxa. This pattern is consistent with the idea that significant distal calcaneal elongation evolved at least twice in early euprimates, and that early primate niche space frequently included demands for increased leaping specialization.

New material of Pseudoloris parvulus (Microchoerinae, Omomyidae, Primates) from the Late Eocene of Sossís (northeastern Spain) and its implications for the evolution of Pseudoloris.

The species Pseudoloris parvulus, identified in several Middle and Late Eocene European sites, was previously known in the Iberian Peninsula by a single mandible preserving P4-M3 from Sossís (Southern Pyrenean Basins, northeastern Spain), described in the 1960s. Further field work at this Late Eocene site has led to the recovery of a large number of mammal remains, including the additional material of P.xa0parvulus described in this paper. Some specimens of P.xa0parvulus from this locality have also been recently found in the collections of the Naturhistorisches Museum Basel, Switzerland. The whole sample consists of 11 mandible fragments including several teeth, three upper dental series and nearly 80 isolated teeth including all of the dental elements, and represents the most complete sample of the genus described from the Iberian Peninsula. This abundant material allows us to provide an emended diagnosis for the species and to observe several directional changes in the dental morphology of the lineage including the species Pseudoloris saalae, Pseudoloris isabenae, Pseudoloris pyrenaicus and P.xa0parvulus. These directional changes include the progressive reduction of the paraconid in the lower molars and the increase in size of the hypocone, metaconule and paraconule in the upper molars. Moreover, despite the overall resemblance among all of the samples ascribed to P.xa0parvulus, we also recognize some differences, particularly an increase in size and better development of the hypocone from the oldest populations of the species, such as Le Bretou, to the most recent ones, like Sossís and Perrière. Therefore, this study sheds new light on the evolution of this genus, which inhabited Europe from the Middle Eocene to the Early Oligocene.

Necrolemur anadoni, a new species of Microchoerinae (Omomyidae, Primates) from the Middle Eocene of Sant Jaume de Frontanyà (Pyrenees, Northeastern Spain)

OBJECTIVESnThe material of Necrolemur (Microchoerinae, Omomyidae, Primates) from the Middle Eocene (Robiacian) locality of Sant Jaume de Frontanyà (Eastern Pyrenees) is described. This is the first confirmable record of this genus from Spain.nnnMETHODSnA mandible fragment bearing P4 -M3 and 15 isolated teeth have been carefully described and compared with all the known species of Necrolemur (namely Necrolemur antiquus, Necrolemur zitteli and Necrolemur cf. zitteli from Egerkingen α) and with Nannopithex filholi.nnnRESULTSnThe studied material shows substantial differences from all previously described forms of Necrolemur and can be erected as a new species. Necrolemur anadoni sp. nov. is characterized by its small size, weak enamel wrinkling, lower molars with the trigonid significantly narrower than the talonid, distinct paraconid in the M1 but poorly differentiated M2 and M3 paraconids, relatively short M3 hypoconulid lobe, M(1-2) with tubercular buccal metaconule, crest-shaped lingual metaconule, hypocone connected to the protocone by a weak postprotocingulum, and M(3) with a very reduced talon basin. It exhibits intermediate size and morphological features between the older Nannopithex filholi and the more recent Necrolemur antiquus.nnnCONCLUSIONSnThis finding allows reinterpretation of the phylogenetic relationships of the known species of Necrolemur. Necrolemur anadoni is considered a direct descendant of Nannopithex filholi and the ancestor of Necrolemur antiquus, whereas Necrolemur zitteli would be a descendant of N. antiquus. Finally, Necrolemur cf. zitteli from Egerkingen most likely evolved independently from N. filholi, being thus separated from the N. filholi-N. anadoni-N. antiquus lineage.

Functional associations between support use and forelimb shape in strepsirrhines and their relevance to inferring locomotor behavior in early primates

The evolution of primates is intimately linked to their initial invasion of an arboreal environment. However, moving and foraging in this milieu creates significant mechanical challenges related to the presence of substrates differing in their size and orientation. It is widely assumed that primates are behaviorally and anatomically adapted to movement on specific substrates, but few explicit tests of this relationship in an evolutionary context have been conducted. Without direct tests of form-function relationships in living primates it is impossible to reliably infer behavior in fossil taxa. In this study, we test a hypothesis of co-variation between forelimb morphology and the type of substrates used by strepsirrhines. If associations between anatomy and substrate use exist, these can then be applied to better understand limb anatomy of extinct primates. The co-variation between each forelimb long bone and the type of substrate used was studied in a phylogenetic context. Our results show that despite the presence of significant phylogenetic signal for each long bone of the forelimb, clear support use associations are present. A strong co-variation was found between the type of substrate used and the shape of the radius, with and without taking phylogeny into account, whereas co-variation was significant for the ulna only when taking phylogeny into account. Species that use a thin branch milieu show radii that are gracile and straight and have a distal articular shape that allows for a wide range of movements. In contrast, extant species that commonly use large supports show a relatively robust and curved radius with an increased surface area available for forearm and hand muscles in pronated posture. These results, especially for the radius, support the idea that strepsirrhine primates exhibit specific skeletal adaptations associated with the supports that they habitually move on. With these robust associations in hand it will be possible to explore the same variables in extinct early primates and primate relatives and thus improve the reliability of inferences concerning substrate use in early primates.

New dental material and redescription of Agerinia roselli (Primates, Adapiformes) from Les Saleres (early Eocene, NE Iberian Peninsula)

In this work, new dental material of Agerinia roselli from its type locality, Les Saleres (NE Spain), is described. An emended diagnosis of the species is provided, together with a redescription of the entire hypodigm from that locality, which was necessary due to some inaccuracies in previous descriptions. The studied material includes 12 teeth (from P3 to M3); the roots of the anterior premolars preserved in a mandible fragment are reported for the first time. Some previously undescribed traits have been identified after the new analysis of this material, such as the P4 with distinct hypoconid and entoconid and the tiny paraconid on the M1. A detailed comparison with other cercamoniines has been made. The body mass of A. roselli, ranging from 650 to 900 g, has also been estimated. The presence of a minuscule paraconid in the M1 is the most reliable criterion for distinguishing this molar from the M2. This is supported by the complete absence of paraconid in four M2 preserved in mandible fragments. The trigonid length seems to be less reliable for distinguishing M1 from M2, due to its high variability in this species. Concluding, this study updates the knowledge about the dental anatomy of A. roselli and demonstrates that it is a valid taxon clearly distinguishable from other cercamoniines.

Microchoerus hookeri nov. sp., a new late Eocene European microchoerine (Omomyidae, Primates): New insights on the evolution of the genus Microchoerus

The study of Eocene primates is crucial for understanding the evolutionary steps undergone by the earliest members of our lineage and the relationships between extinct and extant taxa. Recently, the description of new material from Spain has improved knowledge of European Paleogene primates considerably, particularly regarding microchoerines. Here we describe the remains of Microchoerus from Sossís (late Eocene, Northern Spain), consisting of more than 120 specimens and representing the richest sample of Microchoerus from Spain. This primate was first documented in Sossís during the 1960s, on the basis of scarce specimens that were ascribed to Microchoerus erinaceus. However, the studied material clearly differs from M.xa0erinaceus at its type locality, Hordle Cliff, and shows some characters that allow the erection of a new species, Microchoerus hookeri. This new species is characterized by its medium size, moderate enamel wrinkling, generally absent mesoconid and small hypoconulid in the M1 and M2, single paracone in the upper molars and premolars and, particularly, by the lack of mesostyle in most M1 and M2, a trait not observed in any other species of Microchoerus. Some specimens from Eclépens B (late Eocene, Switzerland), determined previously to be Microcherus aff. erinaceus, are also ascribed to M.xa0hookeri. M.xa0hookeri represents the first step of a lineage that differentiated from Necrolemur antiquus and, later, gave rise to several unnamed forms of Microchoerus, such as those from Euzet and Perrière, finally leading to M.xa0erinaceus. This discovery sheds new light on the complex evolutionary scheme of Microchoerus, indicating that it is most probably a paraphyletic group. A detailed revision of the age of the localities containing remains of Microchoerus and the description of the still unpublished material from some European localities, are necessary to clarify the phylogenetic relationships among the members of this microchoerine group.

Agerinia smithorum sp. nov., a new early Eocene primate from the Iberian Peninsula

The new species Agerinia smithorum (Adapiformes, Primates) from the early Eocene of the Iberian Peninsula is erected in this work. An emended diagnosis of the genus is provided, together with a broad description of the new species and comparisons with other samples assigned to Agerinia and other similar medium-sized cercamoniines. The new species is based on the most complete specimen of this genus published to date, a mandible preserving the alveoli of the canine and P1 , the roots of the P2 and all teeth from P3 to M3 . It was found in Casa Retjo-1, a new early Eocene locality from Northeastern Spain. The studied specimen is clearly distinguishable from other cercamoniines such as Periconodon, Darwinius, and Donrussellia, but very similar to Agerinia roselli, especially in the similar height of P3 and P4 and the general morphology of the molars, therefore allowing the allocation to the same genus. However, it is undoubtedly distinct from A. roselli, having a less molarized P4 and showing a larger paraconid in the M1 and a tiny one in the M2 , among other differences. The body mass of A. smithorum has also been estimated, ranging from 652 to 724 g, similar to that of A. roselli. The primitive traits shown by A. smithorum (moderately molarized P4 , large paraconid in the M1 and small but distinct in the M2 ) suggest that it could be the ancestor of A. roselli.

On the determination of the Microchoerus (Omomyidae, Primates) remains from Sant Cugat de Gavadons (Late Eocene, Ebro Basin, NE Spain).

OBJECTIVESnThe presence of Microchoerus in Sant Cugat de Gavadons (Late Eocene, Ebro Basin, Northeastern Spain) was first noted by M. Crusafont, who described a fragment of maxilla with two teeth that he interpreted as P(4) and M(1) and referred this specimen to the species Microchoerus ornatus. The objective of this work is to study in detail this fossil and check if the previous taxonomic determination was correct.nnnMETHODSnWe reexamine the single specimen from Sant Cugat de Gavadons, providing for the first time detailed descriptions, measurements and illustrations. We also compare this fossil with the holotype of Microchoerus ornatus from Mormont Entreroches (Switzerland) and with the type material of all other described species of Microchoerus.nnnRESULTSnAlthough the scarcity of material from Sant Cugat de Gavadons and the strong wear of the two available teeth (which in fact correspond to P(3) and P(4)) do not allow a determination at the specific level, it is clear that this form presents notable differences with the type of M. ornatus and must not be referred to this species.nnnDISCUSSIONnNeither the anatomical identification of the two teeth of this maxillary fragment, nor the specific determination of the specimen from Sant Cugat de Gavadons was correct. The ascription of this fossil to Microchoerus ornatus, which represented the only mention of the species in the Iberian Peninsula, is no longer valid. Therefore, the known geographical range of M. ornatus remains restricted to Switzerland.

Agerinia marandati sp. nov., a new early Eocene primate from the Iberian Peninsula, sheds new light on the evolution of the genus Agerinia

Background The Eocene was the warmest epoch of the Cenozoic and recorded the appearance of several orders of modern mammals, including the first occurrence of Euprimates. During the Eocene, Euprimates were mainly represented by two groups, adapiforms and omomyiforms, which reached great abundance and diversity in the Northern Hemisphere. Despite this relative abundance, the record of early Eocene primates from the European continent is still scarce and poorly known, preventing the observation of clear morphological trends in the evolution of the group and the establishment of phylogenetic relationships among different lineages. However, knowledge about the early Eocene primates from the Iberian Peninsula has been recently increased through the description of new material of the genus Agerinia from several fossil sites from Northeastern Spain. Methods Here we present the first detailed study of the euprimate material from the locality of Masia de l’Hereuet (early Eocene, NE Spain). The described remains consist of one fragment of mandible and 15 isolated teeth. This work provides detailed descriptions, accurate measurements, high-resolution figures and thorough comparisons with other species of Agerinia as well with other Eurasian notharctids. Furthermore, the position of the different species of Agerinia has been tested with two phylogenetic analyses. Results The new material from Masia de l’Hereuet shows several traits that were previously unknown for the genus Agerinia, such as the morphology of the upper and lower fourth deciduous premolars and the P2, and the unfused mandible. Moreover, this material clearly differs from the other described species of Agerinia, A. roselli and A. smithorum, thus allowing the erection of the new species Agerinia marandati. The phylogenetic analyses place the three species of Agerinia in a single clade, in which A. smithorum is the most primitive species of this genus. Discussion The morphology of the upper molars reinforces the distinction of Agerinia from other notharctids like Periconodon. The analysis of the three described species of the genus, A. smithorum, A. marandati and A. roselli, reveals a progressive change in several morphological traits such as the number of roots and the position of the P1 and P2, the molarization of the P4, the reduction of the paraconid on the lower molars and the displacement of the mental foramina. These gradual modifications allow for the interpretation that these three species, described from the early Eocene of the Iberian Peninsula, are part of a single evolutionary lineage. The stratigraphical position of Masia de l’Hereuet and Casa Retjo-1 (type locality of A. smithorum) and the phylogenetic analyses developed in this work support this hypothesis.

New dental and postcranial material of Agerinia smithorum (Primates, Adapiformes) from the type locality Casa Retjo-1 (early Eocene, Iberian Peninsula)

New material attributed to Agerinia smithorum from Casa Retjo-1 (early Eocene, NE Iberian Peninsula), consisting of 13 isolated teeth and a fragment of calcaneus, is studied in this work. These fossils allow the first description of the calcaneus and the upper premolars for the genus Agerinia, as well as the first description of the P2 and M2 for A.xa0smithorum. The newly recovered lower teeth are virtually identical to the holotype of A.xa0smithorum and are clearly distinguishable from the other species of Agerinia. The upper teeth also show clear differences with Agerinia marandati. The morphology of the calcaneal remains reveals that A.xa0smithorum practiced a moderately active arboreal quadrupedal mode of locomotion, showing less leaping proclivity than notharctines but more than asiadapids. All the morphological features observed in the described material reinforce the hypothesis of a single lineage consisting of the species A.xa0smithorum, A.xa0marandati, and Agerinia roselli. Furthermore, the phylogenetic analysis developed in this work, which incorporates the newly described remains of A.xa0smithorum, maintains the position of Agerinia as closely related to sivaladapids and asiadapids.