Fateh Mebrouk

Early Tertiary mammals from North Africa reinforce the molecular Afrotheria clade

The phylogenetic pattern and timing of the radiation of mammals, especially the geographical origins of major crown clades, are areas of controversy among molecular biologists, morphologists and palaeontologists. Molecular phylogeneticists have identified an Afrotheria clade, which includes several taxa as different as tenrecs (Tenrecidae), golden moles (Chrysochloridae), elephant-shrews (Macroscelididae), aardvarks (Tubulidentata) and paenungulates (elephants, sea cows and hyracoids). Molecular data also suggest a Cretaceous African origin for Afrotheria within Placentalia followed by a long period of endemic evolution on the Afro-Arabian continent after the mid-Cretaceous Gondwanan breakup (approx. 105–25 Myr ago). However, there was no morphological support for such a natural grouping so far. Here, we report new dental and postcranial evidence of Eocene stem hyrax and macroscelidid from North Africa that, for the first time, provides a congruent phylogenetic view with the molecular Afrotheria clade. These new fossils imply, however, substantial changes regarding the historical biogeography of afrotheres. Their long period of isolation in Africa, as assumed by molecular inferences, is now to be reconsidered inasmuch as Eocene paenungulates and elephant-shrews are here found to be related to some Early Tertiary Euramerican ‘hyopsodontid condylarths’ (archaic hoofed mammals). As a result, stem members of afrotherian clades are not strictly African but also include some Early Paleogene Holarctic mammals.

Anthropoid versus strepsirhine status of the African Eocene primates Algeripithecus and Azibius: craniodental evidence.

Recent fossil discoveries have demonstrated that Africa and Asia were epicentres for the origin and/or early diversification of the major living primate lineages, including both anthropoids (monkeys, apes and humans) and crown strepsirhine primates (lemurs, lorises and galagos). Competing hypotheses favouring either an African or Asian origin for anthropoids rank among the most hotly contested issues in paleoprimatology. The Afrocentric model for anthropoid origins rests heavily on the >45 Myr old fossil Algeripithecus minutus from Algeria, which is widely acknowledged to be one of the oldest known anthropoids. However, the phylogenetic position of Algeripithecus with respect to other primates has been tenuous because of the highly fragmentary fossils that have documented this primate until now. Recently recovered and more nearly complete fossils of Algeripithecus and contemporaneous relatives reveal that they are not anthropoids. New data support the idea that Algeripithecus and its sister genus Azibius are the earliest offshoots of an Afro–Arabian strepsirhine clade that embraces extant toothcombed primates and their fossil relatives. Azibius exhibits anatomical evidence for nocturnality. Algeripithecus has a long, thin and forwardly inclined lower canine alveolus, a feature that is entirely compatible with the long and procumbent lower canine included in the toothcomb of crown strepsirhines. These results strengthen an ancient African origin for crown strepsirhines and, in turn, strongly challenge the role of Africa as the ancestral homeland for anthropoids.

Zegdoumyidae (Rodentia, Mammalia), stem anomaluroid rodents from the Early to Middle Eocene of Algeria (Gour Lazib, Western Sahara): new dental evidence

The Palaeogene fossil record of rodents in Africa is very poor compared to that of North America or Eurasia. Despite this, Africa has long appeared to be a centre of adaptive radiation for two distinct groups of Rodentia: Hystricognathi and Anomaluroidea. The >45-million-year-old enigmatic Zegdoumyidae is the oldest and only rodent family known of this age from Africa (Algeria and Tunisia). Zegdoumyids have been tentatively regarded as a possible early African stem group for Anomaluridae, a link that has never been clearly established because of the highly fragmentary nature of zegdoumyid fossils, as well as the major temporal and morphological gaps between zegdoumyids and the first true anomaluroids from the Late Eocene. About 200 rodent teeth have been sorted after acid treatment of indurated sediments from several new localities in the Gour Lazib of western Algeria dating from the late Early or early Middle Eocene. These new fossils allow us to better describe the morphology of the Zegdoumyidae (especially Glibia and Zegdoumys) and to identify a new taxon, Lazibemys zegdouensis gen. et sp. nov. With this material, we investigated the phylogenetic position of the Zegdoumyidae in a high-level rodent phylogeny with cladistic assessment of the dental evidence. Our analyses have yielded six equally most-parsimonious trees in which zegdoumyids represent the earliest offshoots (pectinately arranged) of a large clade that embraces Eocene anomaluroids plus stem and crown Anomaluridae. This phylogenetic assumption underscores the great antiquity of the Anomaluroidea clade in Africa, as expected given the high morphological divergence of the Late Eocene African anomaluroids. Zegdoumyids exhibit a variety of dental morphologies and provide some suggestions on evolutionary trends within the Anomaluroidea (early stages of pentalophodonty, incisor enamel microstructure transitional from the pauciserial to the uniserial condition). The source of Zegdoumyidae is still unclear inasmuch as there is no well-identified sister group among early Palaeogene rodents. Zegdoumyids seem to share a common ancestry with both stem Myodonta and North American Sciuravidae. Given the high degree of dental specialization of zegdoumyids, we cannot exclude the possibility that zegdoumyids are rooted in a more primitive, as yet unknown, African rodent lineage older than the Early-Middle Eocene.

The oldest African bat from the early Eocene of El Kohol (Algeria)

The Afro-Arabian Paleogene fossil record of Chiroptera is very poor. In North Africa and Arabia, this record is limited, thus far, to a few localities mainly in Tunisia (Chambi, late early Eocene), Egypt (Fayum, late Eocene to early Oligocene), and Sultanate of Oman (Taqah, early Oligocene). It consists primarily of isolated teeth or mandible fragments. Interestingly, these African fossil bats document two modern groups (Vespertilionoidea and Rhinolophoidea) from the early Eocene, while the bat fossil record of the same epoch of North America, Eurasia, and Australia principally includes members of the “Eochiroptera.” This paraphyletic group contains all primitive microbats excluding modern families. In Algeria, the region of Brezina, southeast of the Atlas Mountains, is famous for the early Eocene El Kohol Formation, which has yielded one of the earliest mammalian faunas of the African landmass. Recent fieldwork in the same area has led to the discovery of a new vertebrate locality, including isolated teeth of Chiroptera. These fossils represent the oldest occurrence of Chiroptera in Africa, thus extending back the record of the group to the middle early Eocene (Ypresian) on that continent. The material consists of an upper molar and two fragments of lower molars. The dental character association matches that of “Eochiroptera.” As such, although very fragmentary, the material testifies to the first occurrence of “Eochiroptera” in Algeria, and by extension in Africa. This discovery demonstrates that this basal group of Chiroptera had a worldwide distribution during the early Paleogene.

Chronology of the Eocene continental deposits of Africa: Magnetostratigraphy and biostratigraphy of the El Kohol and Glib Zegdou Formations, Algeria

Despite numerous discoveries that have considerably enriched the African-Arabian Tertiary fossil record over the last decades, our knowledge of the evolutionary history of many continental African vertebrate groups during the Paleogene period remains inadequate, particularly when it is compared with the fossil records of Europe or North America. The Eocene Epoch in Africa is especially poorly documented, being restricted to few fossiliferous localities. Our understanding of the early Tertiary emergence, diversification, and paleobiogeographic history of African-Arabian mammals has been further hindered by the lack of a precise temporal framework for these sites. We conducted magnetostratigraphic analyses, associated with biostratigraphic studies, in the fossiliferous sequences exposed in the northwestern Hammadas of the Saharan Platform in the Glib Zegdou area and in the Saharan Atlas at the El Kohol locality (Algeria) to further define the age of these Eocene continental deposits. Based on biostratigraphic constraints, the six polarity zones identified in the El Kohol section can be correlated with chrons C24n to C22r, providing the first direct age estimates for the El Kohol fossiliferous strata between 52 and 51 Ma. Correlation to the geomagnetic polarity time scale, using previously published biostratigraphic data for the Glib Zegdou fauna, suggests an age ranging between 49 and 45 Ma for this section. The high-resolution magnetostratigraphic study of the poorly known continental Eocene Epoch of Algeria provides new insights into the early Tertiary stratigraphy of northwest Africa. The placement of the Algerian localities into a consistent chronological framework constitutes considerable advancement to achieve biostratigraphic correlation of the Paleogene African-Arabian mammal localities.

New philisids (Mammalia, Chiroptera) from the Early–Middle Eocene of Algeria and Tunisia: new insight into the phylogeny, palaeobiogeography and palaeoecology of the Philisidae

Among the Afro-Arabian Palaeogene chiropterans, philisids were the most common and diversified members. The Philisidae are considered as an extinct primitive group of Vespertilionoidea, a well-diversified superfamily that today includes Natalidae, Molossidae and Vespertilionidae. However, the position of Philisidae within this superfamily has never been clearly established. These bats are characterized by a very distinctive dental morphology, and include some representatives that were among the largest bats to be known. Here we describe new dental remains attributable to philisids from the Early–Middle Eocene of Chambi, Tunisia and Gour Lazib area, Algeria. These fossils allow us to reconsider the dental morphology of the oldest philisids: Dizzya exsultans Sigé, 1991 and Witwatia sigei Ravel, 2012. We have undertaken a cladistic assessment of the dental evidence (47 dental and mandible characters) to clarify the phylogenetic relationships within Philisidae, and its position within Vespertilionoidea, in order to highlight the origin, historical biogeography and patterns of dispersion of the most diversified extant bat group. The specialized dental morphology of philisids implies particular occlusion seen in the three-dimensional reconstructions of teeth of Witwatia sigei and Dizzya exsultans. The peculiar morpho-functional anatomy of the teeth and the large size of these bats were well adapted to an opportunistic diet, and probably contributed to the early success of the family in North Africa.

Fossil nutlets of Boraginaceae from the continental Eocene of Hamada of Méridja (southwestern Algeria): The first fossil of the Borage family in Africa

PREMISE OF THE STUDY The Paleogene deposits of the Hamada of Méridja, southwestern Algeria, are currently dated as lower-to-middle Eocene in age based on fossil gastropods and charophytes. Here we report the presence of fruits that can be assigned to the Boraginaceae s.str., apparently representing the first fossil record for this family in Africa, shedding new light on the historical biogeography of this group. METHODS Microscopic studies of the fossil nutlets were carried out and compared to extant Boraginaceae nutlets, and to types reported in the literature for this family. KEY RESULTS The fossils are strikingly similar in general size and morphology, particularly in the finer details of the attachment scar and ornamentation, to nutlets of extant representatives of the Boraginaceae tribe Echiochileae, and especially the genus Ogastemma. We believe that these nutlets represent an extinct member of this lineage. CONCLUSIONS The Ogastemma-like fossils indicate that the Echiochileae, which are most diverse in northern Africa and southwestern Asia, have a long history in this region, dating back to the Eocene. This tribe corresponds to the basal-most clade in Boraginaceae s.str., and the fossils described here agree well with an assumed African origin of the family and the Boraginales I, providing an important additional calibration point for dating the phylogenies of this clade.

Taxonomic review of the “Bulimes”, terrestrial gastropods from the continental Eocene of the Hamada de Méridja (northwestern Sahara, Algeria) (Mollusca: Stylommatophora: Strophocheilidae?), with a discussion of the genera of the family Vidaliellidae

Terrestrial gastropods occur in many North African localities in Eocene continental deposits. Here we analyse the faunal assemblage from the Hamada de Méridja Formation in southwestern Algeria, dated as Early to Middle Eocene on the basis of charophytes. The assemblage consists of three closely related species that to date have been classified either in the extant Madagascan genus Leucotaenius v. Martens, 1860, or in the SW European Eocene genera Romanella Jodot, 1957 and Vicentinia Jodot, 1957. This is rejected for shell morphological and phylogeographical reasons, and a new classification as Maghrebiola gen. nov. is proposed. Maghrebiola is tentatively placed in the South American family Strophocheilidae, as species from the Early Eocene Itaboraí Basin of Brazil, currently placed in the genus Eoborus Klappenbach and Olazarri, 1970 in the family Strophocheilidae, superfamily Acavoidea, have a very similar shell habitus. This record possibly extends the known geographical range of the Strophocheilidae into the African continent during the Eocene. Immigration of this stock into North Africa during the Cretaceous via a still existing plate connection is assumed. An attribution of Maghrebiola to the African family Achatinidae is unlikely for shell morphological reasons despite certain habitus similarities, although the Priabonian genera Arabicolaria and Pacaudiella from Oman most likely belong into this family, and not to the Vidaliellidae as originally proposed. Possible causes for the very low diversity of the assemblage are mainly unfavourable living conditions, i.e. a relatively dry climate resulting in sparse vegetation and only occasional presence of water bodies, which may have had increased salinities, accounting for the lack of freshwater mollusks. The absence of any competing large gastropods may possibly have facilitated high intraspecific variability leading to sympatric occurrence of three closely related species, due to the animals occupying a wide range of available ecological niches. As the species discussed here have also been attributed to the genera Romanella and Vicentinia in the Vidaliellidae, we provide an appendix with annotated characterisations of most genera of the Vidaliellidae and list the nominal species assigned to them. This family is tentatively placed in the South American superfamily Orthalicoidea; its stock would have similarly immigrated from South America, but have successfully colonized mainly SW Europe, with only one Eocene species [Romanella kantarensis (Jodot, 1936)] recognized in Algeria.KurzfassungTerrestrische Gastropoden treten in zahlreichen Lokalitäten Nordafrikas in eozänen kontinentalen Formationen auf. Hier analysieren wir die Faunengemeinschaft der Unteren und Mittleren Subformation einer Abfolge am Südrand der Hamada de Méridja in SW-Algerien, die aufgrund von Charophyten als frühes bis mittleres Eozän datiert ist. Die Faunengemeinschaft besteht aus drei eng verwandten Arten, die bisher entweder der rezenten madegassischen Gattung Leucotaenius v. Martens, 1860, oder den eozänen südeuropäischen Gattungen Romanella Jodot, 1957 und Vicentinia Jodot, 1957 zugeordnet wurden. Dies ist jedoch aufgrund der Gehäusemorphologie und/oder der Phylogeographie unwahrscheinlich, weshalb eine neue Klassifikation als Maghrebiola gen. nov. vorgeschlagen wird. Maghrebiola wird einstweilen der südamerikanischen Familie Strophocheilidae in der Überfamilie Acavoidea zugeordnet, da Arten aus dem frühen Eozän des Itaboraí-Beckens in Brasilien, die z. Zt. innerhalb der Gattung Eoborus Klappenbach und Olazarri, 1970 in die Familie Strophocheilidae gestellt werden, im Gehäusehabitus sehr ähnlich sind. Dieser Nachweis erweitert vorbehaltlich die bekannte geographische Verbreitung der Strophocheilidae bis nach NW-Afrika im Eozän. Eine Einwanderung dieser Linie in N-Afrika während der Kreide über eine noch vorhandene Landverbindung der afrikanischen und südamerikanischen Platte wird angenommen. Die Zuordnung von Maghrebiola zur afrikanischen Familie Achatinidae ist aus gehäusemorphologischen Gründen unwahrscheinlich trotz einer gewissen Habitusähnlichkeit, auch wenn die Gattungen Arabicolaria und Pacaudiella aus dem Priabonium des Omans höchstwahrscheinlich zu dieser Familie gehören und nicht zu den Vidaliellidae, zu denen sie ursprünglich gestellt wurden. Mögliche Gründe für die sehr geringe Diversität der Faunengemeinschaft sind hauptsächlich ungünstige Lebensbedingungen, nämlich ein relativ trockenes Klima, das spärliche Vegetation und nur gelegentlich die Bildung von Wasserkörpern bedingt; letztere könnten erhöhte Salinitäten aufweisen, was das Fehlen von Süßwasser-Mollusken erklären würde. Das Fehlen anderer großer Gastropoden könnte eine hohe intraspezifische Variabilität ermöglicht haben, die zum sympatrischem Vorkommen dreier eng verwandter Arten geführt haben könnte, da die Tiere eine größere Anzahl der vorhandenen ökologischen Nischen besetzt haben könnten. Da die hier behandelten Arten auch in die Gattungen Romanella und Vicentinia (innerhalb der Familie Vidaliellidae) gestellt wurden, präsentieren wir in einem Anhang eine kommentierte Charakterisierung der meisten Gattungen der Vidaliellidae und listen die zugehörigen nominellen Arten auf. Diese Familie wird vorläufig in die südamerikanische Überfamilie Orthalicoidea gestellt. Diese Linie wäre in ähnlicher Weise aus Südamerika eingewandert, hätte aber hauptsächlich SW-Europa kolonisiert, mit nur einer aus Algerien bekannten Art, Romanella kantarensis (Jodot, 1936).