Late Eocene Of Egypt Research Articles

Craniodental and humeral morphology of a new species of Masrasector (Teratodontinae, Hyaenodonta, Placentalia) from the late Eocene of Egypt and locomotor diversity in hyaenodonts.

Hyaenodonta is a diverse clade of carnivorous mammals that were part of terrestrial faunas in the Paleogene of Eurasia and North America, but the oldest record for the group is Afro-Arabian, making the record there vital for understanding the evolution of this wide-spread group. Previous studies show an ancient split between two major clades of hyaenodonts that converged in hypercarnivory: Hyainailourinae and Hyaenodontinae. These clades are each supported by cranial characters. Phylogenetic analyses of hyaenodonts also support the monophyly of Teratodontinae, an Afro-Arabian clade of mesocarnivorous to hypercarnivorous hyaenodonts. Unfortunately, the cranial anatomy of teratodontines is poorly known, and aligning the clade with other lineages has been difficult. Here, a new species of the phylogenetically controversial teratodontine Masrasector is described from Locality 41 (latest Priabonian, late Eocene) from the Fayum Depression, Egypt. The hypodigm includes the most complete remains of a Paleogene teratodontine, including largely complete crania, multiple dentaries, and isolated humeri. Standard and “tip-dating” Bayesian analyses of a character-taxon matrix that samples cranial, postcranial, and dental characters support a monophyletic Masrasector within Teratodontinae, which is consistently placed as a close sister group of Hyainailouridae. The cranial morphology of Masrasector provides new support for an expanded Hyainailouroidea (Teratodontinae + Hyainailouridae), particularly characters of the nuchal crest, palate, and basicranium. A discriminant function analysis was performed using measurements of the distal humerus from a diverse sample of extant carnivorans to infer the locomotor habits of Masrasector. Masrasector was assigned to the “terrestrial” locomotor category, a result consistent with the well-defined medial trochlear ridges, and moderately developed supinator crests of the specimens. Masrasector appears to have been a fast-moving terrestrial form with a diverse diet. These specimens considerably improve our understanding of Teratodontinae, an ancient member of the Afro-Arabian mammalian fauna, and our understanding of hyaenodont diversity before the dispersal of Carnivora to the continent near the end of the Paleogene.

New adapiform primate fossils from the late Eocene of Egypt

Caenopithecine adapiform primates are currently represented by two genera from the late Eocene of Egypt (Afradapis and Aframonius) and one from the middle Eocene of Switzerland (Caenopithecus). All are somewhat anthropoid-like in several aspects of their dental and gnathic morphology, and are inferred to have been highly folivorous. Here we describe a new caenopithecine genus and species, Masradapis tahai, from the ~37 million-year-old Locality BQ-2 in Egypt, that is represented by mandibular and maxillary fragments and isolated teeth. Masradapis is approximately the same size as Aframonius but differs in having a more dramatic distal increase in molar size, more complex upper molar shearing crests, and an exceptionally deep mandibular corpus. We also describe additional mandibles and part of the orbit and rostrum of Aframonius which suggest that it was probably diurnal. Phylogenetic analyses place Masradapis either as the sister taxon of Aframonius (parsimony), or as the sister taxon of Afradapis and Caenopithecus (Bayesian methods). Bayesian tip-dating analysis, when combined with Bayesian biogeographic analysis, suggests that a common ancestor of known caenopithecines dispersed to Afro-Arabia from Europe between 49.4 and 47.4 Ma, and that a trans-Tethyan back-dispersal explains Caenopithecus’ later presence in Europe.For Masradapis: https://www.zoobank.org/urn:lsid:zoobank.org:act:41BC8459-7CCE-487F-BC59-1C34257D5C4EFor Masradapis tahai: https://www.zoobank.org/urn:lsid:zoobank.org:act:C0A620AD-6FCA-4649-A980-FCA237AFE39D

Hyainailourine and teratodontine cranial material from the late Eocene of Egypt and the application of parsimony and Bayesian methods to the phylogeny and biogeography of Hyaenodonta (Placentalia, Mammalia).

Hyaenodonta is a diverse, extinct group of carnivorous mammals that included weasel- to rhinoceros-sized species. The oldest-known hyaenodont fossils are from the middle Paleocene of North Africa and the antiquity of the group in Afro-Arabia led to the hypothesis that it originated there and dispersed to Asia, Europe, and North America. Here we describe two new hyaenodont species based on the oldest hyaenodont cranial specimens known from Afro-Arabia. The material was collected from the latest Eocene Locality 41 (L-41, ∼34 Ma) in the Fayum Depression, Egypt. Akhnatenavus nefertiticyon sp. nov. has specialized, hypercarnivorous molars and an elongate cranial vault. In A. nefertiticyon the tallest, piercing cusp on M1–M2 is the paracone. Brychotherium ephalmos gen. et sp. nov. has more generalized molars that retain the metacone and complex talonids. In B. ephalmos the tallest, piercing cusp on M1–M2 is the metacone. We incorporate this new material into a series of phylogenetic analyses using a character-taxon matrix that includes novel dental, cranial, and postcranial characters, and samples extensively from the global record of the group. The phylogenetic analysis includes the first application of Bayesian methods to hyaenodont relationships. B. ephalmos is consistently placed within Teratodontinae, an Afro-Arabian clade with several generalist and hypercarnivorous forms, and Akhnatenavus is consistently recovered in Hyainailourinae as part of an Afro-Arabian radiation. The phylogenetic results suggest that hypercarnivory evolved independently three times within Hyaenodonta: in Teratodontinae, in Hyainailourinae, and in Hyaenodontinae. Teratodontines are consistently placed in a close relationship with Hyainailouridae (Hyainailourinae + Apterodontinae) to the exclusion of “proviverrines,” hyaenodontines, and several North American clades, and we propose that the superfamily Hyainailouroidea be used to describe this relationship. Using the topologies recovered from each phylogenetic method, we reconstructed the biogeographic history of Hyaenodonta using parsimony optimization (PO), likelihood optimization (LO), and Bayesian Binary Markov chain Monte Carlo (MCMC) to examine support for the Afro-Arabian origin of Hyaenodonta. Across all analyses, we found that Hyaenodonta most likely originated in Europe, rather than Afro-Arabia. The clade is estimated by tip-dating analysis to have undergone a rapid radiation in the Late Cretaceous and Paleocene; a radiation currently not documented by fossil evidence. During the Paleocene, lineages are reconstructed as dispersing to Asia, Afro-Arabia, and North America. The place of origin of Hyainailouroidea is likely Afro-Arabia according to the Bayesian topologies but it is ambiguous using parsimony. All topologies support the constituent clades–Hyainailourinae, Apterodontinae, and Teratodontinae–as Afro-Arabian and tip-dating estimates that each clade is established in Afro-Arabia by the middle Eocene.

Morphometric analysis of Paleogene Loxoconcha species (Crustacea, Ostracoda) from Egypt and Tunisia

Three Loxoconcha species from the Paleocene–Eocene successions of Egypt are closely related to each other; namely: Loxoconcha saharaensis (L. saharaensis) Bassiouni & Luger from the Late Paleocene of Egypt, Loxoconcha blanckenhorni (L. blanckenhorni) Bassiouni & Luger from the Early Eocene of Egypt, and Loxoconcha pseudopunctatella (L. pseudopunctatella) Cronin & Khalifa from the Middle to Late Eocene of Egypt. Other related forms have been identified from the Early Eocene of Egypt and the Late Paleocene of Tunisia. Relative warp analysis could differentiate among the three studied species on the basis of sexual dimorphism. Thin-plate spline analysis suggests that the related forms from Egypt and Tunisia are intermediate forms between L. saharaensis and L. blanckenhorni, with closer similarity to L. saharaensis. Therefore, the holotype of L. saharaensis is defined herein as morphotype A, the specimen from Tunisia as morphotype B, and the specimen from Egypt as morphotype C. Moreover, the results indicate that the Middle Eocene species (L. pseudopunctatella) is closer to the Early Eocene species (L. blanckenhorni) than to the Late Paleocene species (L. saharaensis). A probable evolutionary trend is detected within the studied L. saharaensis morphs from the Late Paleocene of Egypt and Tunisia to the Early Eocene of Egypt. This trend was more or less simultaneous with decreasing size above the PETM level. A similar lineage and size reduction was detected between the Early Eocene species L. blanckenhorni and the Middle Eocene species L. pseudopunctatella.

New phiomorph rodents from the latest Eocene of Egypt, and the impact of Bayesian "clock"-based phylogenetic methods on estimates of basal hystricognath relationships and biochronology.

The Fayum Depression of Egypt has yielded fossils of hystricognathous rodents from multiple Eocene and Oligocene horizons that range in age from ∼37 to ∼30 Ma and document several phases in the early evolution of crown Hystricognathi and one of its major subclades, Phiomorpha. Here we describe two new genera and species of basal phiomorphs, Birkamys korai and Mubhammys vadumensis, based on rostra and maxillary and mandibular remains from the terminal Eocene (∼34 Ma) Fayum Locality 41 (L-41). Birkamys is the smallest known Paleogene hystricognath, has very simple molars, and, like derived Oligocene-to-Recent phiomorphs (but unlike contemporaneous and older taxa) apparently retained dP4∕4 late into life, with no evidence for P4∕4 eruption or formation. Mubhammys is very similar in dental morphology to Birkamys, and also shows no evidence for P4∕4 formation or eruption, but is considerably larger. Though parsimony analysis with all characters equally weighted places Birkamys and Mubhammys as sister taxa of extant Thryonomys to the exclusion of much younger relatives of that genus, all other methods (standard Bayesian inference, Bayesian “tip-dating,” and parsimony analysis with scaled transitions between “fixed” and polymorphic states) place these species in more basal positions within Hystricognathi, as sister taxa of Oligocene-to-Recent phiomorphs. We also employ tip-dating as a means for estimating the ages of early hystricognath-bearing localities, many of which are not well-constrained by geological, geochronological, or biostratigraphic evidence. By simultaneously taking into account phylogeny, evolutionary rates, and uniform priors that appropriately encompass the range of possible ages for fossil localities, dating of tips in this Bayesian framework allows paleontologists to move beyond vague and assumption-laden “stage of evolution” arguments in biochronology to provide relatively rigorous age assessments of poorly-constrained faunas. This approach should become increasingly robust as estimates are combined from multiple independent analyses of distantly related clades, and is broadly applicable across the tree of life; as such it is deserving of paleontologists’ close attention. Notably, in the example provided here, hystricognathous rodents from Libya and Namibia that are controversially considered to be of middle Eocene age are instead estimated to be of late Eocene and late Oligocene age, respectively. Finally, we reconstruct the evolution of first lower molar size among Paleogene African hystricognaths using a Bayesian approach; the results of this analysis reconstruct a rapid latest Eocene dwarfing event along the lineage leading to Birkamys.

Primate tarsal bones from Egerkingen, Switzerland, attributable to the middle Eocene adapiform Caenopithecus lemuroides.

The middle Eocene species Caenopithecus lemuroides, known solely from the Egerkingen fissure fillings in Switzerland, was the first Paleogene fossil primate to be correctly identified as such (by Ludwig Rütimeyer in 1862), but has long been represented only by fragmentary mandibular and maxillary remains. More recent discoveries of adapiform fossils in other parts of the world have revealed Caenopithecus to be a biogeographic enigma, as it is potentially more closely related to Eocene adapiforms from Africa, Asia, and North America than it is to any known European forms. More anatomical evidence is needed, however, to provide robust tests of such phylogenetic hypotheses. Here we describe and analyze the first postcranial remains that can be attributed to C. lemuroides—an astragalus and three calcanei held in the collections of the Naturhistorisches Museum Basel that were likely recovered from Egerkingen over a century ago. Qualitative and multivariate morphometric analyses of these elements suggest that C. lemuroides was even more loris-like than European adapines such as Adapis and Leptadapis, and was not simply an adapine with an aberrant dentition. The astragalus of Caenopithecus is similar to that of younger Afradapis from the late Eocene of Egypt, and parsimony and Bayesian phylogenetic analyses that include the new tarsal data strongly support the placement of Afradapis and Caenopithecus as sister taxa to the exclusion of all other known adapiforms, thus implying that dispersal between Europe and Africa occurred during the middle Eocene. The new tarsal evidence, combined with previously known craniodental fossils, allows us to reconstruct C. lemuroides as having been an arboreal and highly folivorous 1.5–2.5 kg primate that likely moved slowly and deliberately with little or no capacity for acrobatic leaping, presumably maintaining consistent powerful grasps on branches in both above-branch and inverted postures.

The fossil record of Glypturus (Decapoda: Axiidea: Callianassidae) revisited with additional observations and description of a new species

The extent of propodal tuberculation is considered taxonomically important for species of the callianassid genus Glypturus (Decapoda: Axiidea). Based on cheliped material from the Middle-Late Miocene of Iran, Glypturuspersicus n. sp. is described here. It possesses no tuberculation on the outer surface of the major propodus, whereas its inner surface is moderately to heavily tuberculated in terms of its extent. It resembles extant Glypturus armatus, but this species is completely smooth on both propodal surfaces. A reappraisal of Glypturus toulai from the Early and Late Miocene of Panama is presented. Additionally, the type material of Glypturus fraasi from the Late Eocene of Egypt is figured. In the nature of tuberculation, an evolutionary trend is observable in Glypturus with the most tuberculated forms from the Palaeogene and less tuberculated forms from the Neogene. This trend is clearly seen in the possible West Atlantic lineage of the genus.

Last of the oligopithecids? A dwarf species from the youngest primate-bearing level of the Jebel Qatrani Formation, northern Egypt

Oligopithecids are basal stem catarrhines that make their first definitive appearance in the fossil record in the latest Eocene of Egypt. Previously, the group was assumed to have gone locally extinct in northern Africa shortly after the Eocene–Oligocene boundary, with a last record at the ∼31.5 Ma Taqah locality in Oman. Here we describe a tiny oligopithecid from the youngest (∼29.5–30 Ma) primate-bearing horizon in the Jebel Qatrani Formation, based on a partial hemimandible with a largely complete first molar. This is the first record of an oligopithecid in the upper sequence of that Formation, occurring ∼160 m above the next-youngest oligopithecid-bearing locality (Quarry E), and provides a new last appearance datum for Oligopithecidae. The species is markedly smaller than its older oligopithecid relatives Catopithecus and Oligopithecus, and indeed is one of the smallest anthropoids known, suggesting that it represents a member of a dwarfed lineage. This material adds to the evidence provided by the co-occurring species Afrotarsius chatrathi and Qatrania fleaglei for a fairly diverse, but exceedingly rare, small primate fauna at a horizon that is otherwise dominated by much larger and more derived propliopithecids and parapithecids.

A large-bodied anomaluroid rodent from the earliest late Eocene of Egypt: phylogenetic and biogeographic implications

ABSTRACT A new genus and species of anomaluroid rodent, Kabirmys qarunensis, is described based on isolated teeth, partial mandibles, and an edentulous partial maxilla from the earliest late Eocene Birket Qarun Locality 2 (BQ-2) in the Fayum Depression of northern Egypt. Kabirmys is the largest known Paleogene anomaluroid, with first lower molar area being about 2.5 times that of the roughly contemporaneous Nementchamys and Pondaungimys from Algeria and Myanmar, respectively. The genus exhibits distinctive features not seen in other Paleogene taxa, such as a complete mure, weak neo-endoloph, and open lingual sinus on the upper molars; Kabirmys lacks the complex enamel crenulations seen in Nementchamys and Pondaungimys. Phylogenetic analysis of dental features nests Kabirmys within crown Anomaluridae as a sister taxon of Nementchamys and Pondaungimys, but parsimony analysis following addition of a chronobiogeographic character places all of these taxa as basal stem members of Anomaluridae. This new evidence indicates that there was considerable diversity in body size and molar morphology among African anomaluroids near the middle-late Eocene boundary, and suggests that the group had an ancient origin on that landmass. Kabirmys shares some primitive features with the possible zegdoumyid ‘Glibia’ namibiensis from the Paleogene of Namibia, and suggests that anomaluroids might be derived from a zegdoumyid-like ancestor. The disappearance of anomaluroids in the upper (latest Eocene to early Oligocene) levels of the Fayum succession might be related to global cooling through the later Paleogene, which might have removed suitable habitats from northern Africa.

A highly derived anomalurid rodent (Mammalia) from the earliest Late Eocene of Egypt

Abstract: A new genus and species of diminutive anomalurid rodent, Shazurus minutus, is described on the basis of 15 isolated teeth from the earliest late Eocene (approximately 37 Ma) Birket Qarun Locality 2 in the Fayum Depression of northern Egypt. Shazurus is surprisingly specialized for its age, being most similar in dental morphology to early Miocene Paranomalurus and extant Anomalurus, and is quite different from the roughly contemporaneous anomaluroid genera Nementchamys and Pondaungimys from Algeria and Myanmar, respectively. Parsimony analysis of dental features places Shazurus within crown Anomaluridae as a sister group of two species of Paranomalurus to the exclusion of extant Anomalurus and Idiurus. The marked morphological differences between the two oldest Afro-Arabian anomaluroids (Shazurus and Nementchamys) suggest that the taxa share a much more ancient common Afro-Arabian ancestor, possibly derived from Zegdoumyidae. Isolated teeth of Shazurus and other Eocene anomaluroids reveal little about their palaeobiology, but the complete absence of Anomaluroidea from the younger (late Eocene to early Oligocene) Jebel Qatrani Formation is presumably a reflection of environmental change through the late Eocene in northern Africa.

Redescription of the Skull of Dacquemys Williams, 1954, a Podocnemidid Side-Necked Turtle from the Late Eocene of Egypt

The known material of the side-necked turtle Dacquemys paleomorpha Williams, 1954, consists of the type skull and a new skull from the late Eocene of Egypt. Dacquemys is reaffirmed as a member of the Podocnemididae because of its well-developed cavum pterygoideus. Within the Podocnemididae Dacquemys uniquely possesses a fully roofed temporal region produced by a posteriorly extensive parietal and wide supraoccipital, a very wide interorbital area, and two accessory maxillary ridges meeting anteriorly to form an enclosed trough.

Anthropoid humeri from the late Eocene of Egypt.

A number of recent studies have, by necessity, placed a great deal of emphasis on the dental evidence for Paleogene anthropoid interrelationships, but cladistic analyses of these data have led to the erection of phylogenetic hypotheses that appear to be at odds with biogeographic and stratigraphic considerations. Additional morphological data from the cranium and postcranium of certain poorly understood Paleogene primates are clearly needed to help test whether such hypotheses are tenable. Here we describe humeri attributable to Proteopithecus sylviae and Catopithecus browni, two anthropoids from late Eocene sediments of the Fayum Depression in Egypt. Qualitative and morphometric analyses of these elements indicate that humeri of the oligopithecine Catopithecus are more similar to early Oligocene propliopithecines than they are to any other Paleogene anthropoid taxon, and that Proteopithecus exhibits humeral similarities to parapithecids that may be symplesiomorphies of extant (or "crown") Anthropoidea. The humeral morphology of Catopithecus is consistent with certain narrowly distributed dental apomorphies-such as the loss of the upper and lower second premolar and the development of a honing blade for the upper canine on the lower third premolar-which suggest that oligopithecines constitute the sister group of a clade containing propliopithecines and Miocene-Recent catarrhines and are not most closely related to Proteopithecus as has recently been proposed.

Widanelfarasia, a diminutive placental from the late Eocene of Egypt.

The lower dentition of Widanelfarasia (new genus), a diminutive late Eocene placental from the Fayum Depression in Egypt, is described. Widanelfarasia exhibits a complex of features associated with incipient zalambdodonty and at least three unequivocal apomorphies [loss of P(1), an enlarged I(2) (relative to I(3)), and a basal cusp on I(2)], which provide weak support for its placement as a possible sister taxon of either a tenrecid-chrysochlorid clade or of solenodontids. The former hypothesis gains additional support from biogeographical evidence, but both scenarios are currently tenuous as Widanelfarasia is clearly not truly zalambdodont. Phylogenetic hypotheses positing affinities with tenrecids alone or chrysochlorids alone must invoke either convergent acquisition of zalambdodonty in these taxa or autapomorphic reversal in Widanelfarasia. Given these considerations, a relationship with more generalized taxa from the Laurasian Paleogene (e.g., geolabidids, nyctitheriids, leptictids) cannot yet be ruled out. Comparisons with other Paleogene Afro-Arabian forms are generally inconclusive. A relationship with the earlier Eocene Chambilestes from Tunisia-currently represented by a single specimen preserving P(4)-M(3)-seems possible based on the geometry and predicted occlusal relationships of these teeth, but cannot be confidently determined until these two taxa come to be represented by common diagnostic elements. Todralestes (late Paleocene, Morocco) exhibits general phenetic similarities to Widanelfarasia, but it is not yet known whether this taxon shares any of Widanelfarasia's unequivocal dental apomorphies. Pending the recovery of more informative material, we tentatively refer Widanelfarasia to Placentalia incertae sedis. Truly zalambdodont placentals remain conspicuously absent from the Paleogene of Afro-Arabia.