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Ocepeia (Middle Paleocene of Morocco): the oldest skull of an afrotherian mammal.

Gheerbrant E, Amaghzaz M, Bouya B, Goussard F, Letenneur C - PLoS ONE (2014)

Bottom Line: This results from conflict with undetected convergences of Paenungulata and Perissodactyla in our cladistic analysis, such as the shared bilophodonty.The selenodont pattern best supports the stem paenungulate position of Ocepeia; that, however, needs further support.In addition, the autapomorphic family Ocepeiidae supports the old--earliest Tertiary or Cretaceous--endemic evolution of placentals in Africa, in contrast to hypotheses rooting afrotherians in Paleogene Laurasian "condylarths".

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, CNRS-MNHN-UPMC, Muséum National d'Histoire Naturelle, Dpnt Histoire de la Terre, Paris, France.

ABSTRACT
While key early(iest) fossils were recently discovered for several crown afrotherian mammal orders, basal afrotherians, e.g., early Cenozoic species that comprise sister taxa to Paenungulata, Afroinsectiphilia or Afrotheria, are nearly unknown, especially in Africa. Possible stem condylarth-like relatives of the Paenungulata (hyraxes, sea-cows, elephants) include only Abdounodus hamdii and Ocepeia daouiensis from the Selandian of Ouled Abdoun Basin, Morocco, both previously only documented by lower teeth. Here, we describe new fossils of Ocepeia, including O.grandis n. sp., and a sub-complete skull of O. daouiensis, the first known before the Eocene for African placentals. O.daouiensis skull displays a remarkable mosaic of autapomophic, ungulate-like and generalized eutherian-like characters. Autapomorphies include striking anthropoid-like characters of the rostrum and dentition. Besides having a basically eutherian-like skull construction, Ocepeia daouiensis is characterized by ungulate-like, and especially paenungulate-like characters of skull and dentition (e.g., selenodonty). However, some plesiomorphies such as absence of hypocone exclude Ocepeia from crown Paenungulata. Such a combination of plesiomorphic and derived characters best fits with a stem position of Ocepeia relative to Paenungulata. In our cladistic analyses Ocepeia is included in Afrotheria, but its shared derived characters with paenungulates are not optimized as exclusive synapomorphies. Rather, within Afrotheria Ocepeia is reconstructed as more closely related to insectivore-like afroinsectiphilians (i.e., aardvarks, sengis, tenrecs, and golden moles) than to paenungulates. This results from conflict with undetected convergences of Paenungulata and Perissodactyla in our cladistic analysis, such as the shared bilophodonty. The selenodont pattern best supports the stem paenungulate position of Ocepeia; that, however, needs further support. The remarkable character mosaic of Ocepeia makes it the first known "transitional fossil" between insectivore-like and ungulate-like afrotherians. In addition, the autapomorphic family Ocepeiidae supports the old--earliest Tertiary or Cretaceous--endemic evolution of placentals in Africa, in contrast to hypotheses rooting afrotherians in Paleogene Laurasian "condylarths".

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Ocepeia daouiensis, Selandian, Phosphate level IIa of Sidi Chennane, Ouled Abdoun Basin, Morocco O. daouiensis. Reconstruction of the skull.Lateral view. This reconstruction of the skull is based on the female specimen MNHN.F PM45. The specimen MNHN.F PM54, a male individual, is distinct from MNHN.F PM45 with a more robust skull morphology and presence of a stronger sagittal crest. The dashed line (hatched area) at skull roof corresponds to our estimated correction of the plastic dorso-ventral crushing of MNHN.F PM45 that could not be quantified precisely on this specimen, even with the CT scans (see comments in text, §Reconstruction); the correction is based on comparison with MNHN.F PM54. The lower jaw was reconstructed based on specimen MNHN.F PM41 [26]. Drawings: C. Letenneur (MNHN).
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pone-0089739-g012: Ocepeia daouiensis, Selandian, Phosphate level IIa of Sidi Chennane, Ouled Abdoun Basin, Morocco O. daouiensis. Reconstruction of the skull.Lateral view. This reconstruction of the skull is based on the female specimen MNHN.F PM45. The specimen MNHN.F PM54, a male individual, is distinct from MNHN.F PM45 with a more robust skull morphology and presence of a stronger sagittal crest. The dashed line (hatched area) at skull roof corresponds to our estimated correction of the plastic dorso-ventral crushing of MNHN.F PM45 that could not be quantified precisely on this specimen, even with the CT scans (see comments in text, §Reconstruction); the correction is based on comparison with MNHN.F PM54. The lower jaw was reconstructed based on specimen MNHN.F PM41 [26]. Drawings: C. Letenneur (MNHN).

Mentions: The lower jaw reconstructed in Figure 12 is based primarily on specimen PM41, and other specimens for the anterior dentition (see [26]).


Ocepeia (Middle Paleocene of Morocco): the oldest skull of an afrotherian mammal.

Gheerbrant E, Amaghzaz M, Bouya B, Goussard F, Letenneur C - PLoS ONE (2014)

Ocepeia daouiensis, Selandian, Phosphate level IIa of Sidi Chennane, Ouled Abdoun Basin, Morocco O. daouiensis. Reconstruction of the skull.Lateral view. This reconstruction of the skull is based on the female specimen MNHN.F PM45. The specimen MNHN.F PM54, a male individual, is distinct from MNHN.F PM45 with a more robust skull morphology and presence of a stronger sagittal crest. The dashed line (hatched area) at skull roof corresponds to our estimated correction of the plastic dorso-ventral crushing of MNHN.F PM45 that could not be quantified precisely on this specimen, even with the CT scans (see comments in text, §Reconstruction); the correction is based on comparison with MNHN.F PM54. The lower jaw was reconstructed based on specimen MNHN.F PM41 [26]. Drawings: C. Letenneur (MNHN).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3935939&req=5

pone-0089739-g012: Ocepeia daouiensis, Selandian, Phosphate level IIa of Sidi Chennane, Ouled Abdoun Basin, Morocco O. daouiensis. Reconstruction of the skull.Lateral view. This reconstruction of the skull is based on the female specimen MNHN.F PM45. The specimen MNHN.F PM54, a male individual, is distinct from MNHN.F PM45 with a more robust skull morphology and presence of a stronger sagittal crest. The dashed line (hatched area) at skull roof corresponds to our estimated correction of the plastic dorso-ventral crushing of MNHN.F PM45 that could not be quantified precisely on this specimen, even with the CT scans (see comments in text, §Reconstruction); the correction is based on comparison with MNHN.F PM54. The lower jaw was reconstructed based on specimen MNHN.F PM41 [26]. Drawings: C. Letenneur (MNHN).
Mentions: The lower jaw reconstructed in Figure 12 is based primarily on specimen PM41, and other specimens for the anterior dentition (see [26]).

Bottom Line: This results from conflict with undetected convergences of Paenungulata and Perissodactyla in our cladistic analysis, such as the shared bilophodonty.The selenodont pattern best supports the stem paenungulate position of Ocepeia; that, however, needs further support.In addition, the autapomorphic family Ocepeiidae supports the old--earliest Tertiary or Cretaceous--endemic evolution of placentals in Africa, in contrast to hypotheses rooting afrotherians in Paleogene Laurasian "condylarths".

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, CNRS-MNHN-UPMC, Muséum National d'Histoire Naturelle, Dpnt Histoire de la Terre, Paris, France.

ABSTRACT
While key early(iest) fossils were recently discovered for several crown afrotherian mammal orders, basal afrotherians, e.g., early Cenozoic species that comprise sister taxa to Paenungulata, Afroinsectiphilia or Afrotheria, are nearly unknown, especially in Africa. Possible stem condylarth-like relatives of the Paenungulata (hyraxes, sea-cows, elephants) include only Abdounodus hamdii and Ocepeia daouiensis from the Selandian of Ouled Abdoun Basin, Morocco, both previously only documented by lower teeth. Here, we describe new fossils of Ocepeia, including O.grandis n. sp., and a sub-complete skull of O. daouiensis, the first known before the Eocene for African placentals. O.daouiensis skull displays a remarkable mosaic of autapomophic, ungulate-like and generalized eutherian-like characters. Autapomorphies include striking anthropoid-like characters of the rostrum and dentition. Besides having a basically eutherian-like skull construction, Ocepeia daouiensis is characterized by ungulate-like, and especially paenungulate-like characters of skull and dentition (e.g., selenodonty). However, some plesiomorphies such as absence of hypocone exclude Ocepeia from crown Paenungulata. Such a combination of plesiomorphic and derived characters best fits with a stem position of Ocepeia relative to Paenungulata. In our cladistic analyses Ocepeia is included in Afrotheria, but its shared derived characters with paenungulates are not optimized as exclusive synapomorphies. Rather, within Afrotheria Ocepeia is reconstructed as more closely related to insectivore-like afroinsectiphilians (i.e., aardvarks, sengis, tenrecs, and golden moles) than to paenungulates. This results from conflict with undetected convergences of Paenungulata and Perissodactyla in our cladistic analysis, such as the shared bilophodonty. The selenodont pattern best supports the stem paenungulate position of Ocepeia; that, however, needs further support. The remarkable character mosaic of Ocepeia makes it the first known "transitional fossil" between insectivore-like and ungulate-like afrotherians. In addition, the autapomorphic family Ocepeiidae supports the old--earliest Tertiary or Cretaceous--endemic evolution of placentals in Africa, in contrast to hypotheses rooting afrotherians in Paleogene Laurasian "condylarths".

Show MeSH
Related in: MedlinePlus