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E.L. Simons

Publications and source records attributed to E.L. Simons.

6 recordsLinked to original sources
USGS2009

THE subfossil occurrence and paleoecological significance of small mammals at ankilitelo cave, southwestern Madagascar

Small mammals are rarely reported from subfossil sites in Madagascar despite their importance for paleoenvironmental reconstruction, especially as it relates to recent ecological changes on the island. We describe the uniquely rich subfossil small mammal fauna from Ankilitelo Cave, southwestern Madagascar. The Ankilitelo fauna is dated to the late Holocene (∼500 years ago), documenting the youngest appearances of the extinct giant lemur taxa Palaeopropithecus, Megaladapis , and Archaeolemur , in association with abundant remains of small vertebrates, including bats, tenrecs, carnivorans, rodents, and primates. The Ankilitelo fauna is composed of 34 mammalian species, making it one of the most diverse Holocene assemblages in Madagascar. The fauna comprises the 1st report of the short-tailed shrew tenrec ( Microgale brevicaudata ) and the ring-tailed mongoose ( Galidia elegans ) in southwestern Madagascar. Further, Ankilitelo documents the presence of southwestern species that are rare or that have greatly restricted ranges today, such as Nasolo's shrew tenrec ( M. nasoloi ), Grandidier's mongoose ( Galidictis grandidieri ), the narrow-striped mongoose ( Mungotictis decemlineata ), and the giant jumping rat ( Hypogeomys antimena ). A simple cause for the unusual small mammal occurrences at Ankilitelo is not obvious. Synergistic interactions between climate change, recent fragmentation and human-initiated degradation of forested habitats, and community-level processes, such as predation, most likely explain the disjunct distributions of the small mammals documented at Ankilitelo.

Journal of Mammalogy↗
USGS2006

Sexual dimorphism of the internal mandibular chamber in Fayum Pliohyracidae (Mammalia)

An internal mandibular fenestra and chamber are found in many fossil hyracoids. The internal mandibular fenestra is located on the lingual surface of the mandibular corpus and opens into a chamber within the mandible. The mandibular chamber is maximally developed in late Eocene Thyrohyrax meyeri and early Oligocene Thyrohyrax domorictus from the Fayum Province of Egypt. The function of this chamber is unknown as it is not found in extant hyraxes, nor is it known to occur in any other mammal. In Thyrohyrax, this feature appears to be sexually dimorphic because it is confined to roughly one half of the specimens that otherwise cannot be separated by dental characteristics or measurements. It has been suggested that the chamber is found in females based on the presumed distribution of this character in other fossil hyracoids. Fossils from Fayum Quarry L-41, preserving the sexually dimorphic anterior dentition, show that, in Thyrohyrax meyeri and Thyrohyrax domorictus, the internal mandibular chamber is found in males. In Thyrohyrax litholagus, an internal mandibular fenestra and inflated mandibular chamber occurs in males whereas females show the variable presence of an internal mandibular fossa or fenestra but lack an expanded chamber. Other genera show differing patterns of sexual variation in which some Fayum hyracoids have an internal mandibular fenestra in both sexes but with the greatest development of the mandibular chamber occurring in males. We review functions proposed for the internal mandibular chamber and suggest that it housed a laryngeal air sac that may have had a vocal function by acting as a resonating chamber. ?? 2006 by the Society of Vertebrate Paleontology.

Journal of Vertebrate Paleontology↗
USGS1985

Afrotarsius chatrathi, first tarsiiform primate (? Tarsiidae) from Africa

Tarsiiform primates have long been regarded as a Laurasian group, with an extensive fossil record in the Eocene of North America and Europe1-4 and two important but less well-known records from Asia5,6. The only living genus is Tarsius (Tarsiidae), whereas all of the fossil tarsier-like primates are usually placed in the extinct family Omomyidae3. We now report the discovery of Afrotarsius chatrathi from early Oligocene rocks of Fayum Province, Egypt. This is the first known tarsiiform primate from Africa. Compared with fossil primates, the molar tooth morphology of this diminutive prosimian is most similar to that of the European Eocene microchoerine Pseudoloris; however, the closest similarity is to the molars of Tarsius. Because the phylogenetic relationships among living Tarsius and the omomyids remain unclear7,8 and because of the fragmentary nature of the only known specimen of this new primate, allocation of Afrotarsius to either Omomyidae or Tarsiidae is necessarily provisional. As we believe that its molar teeth are more like those of Tarsius than of any omomyids (including Pseudoloris), we tentatively assign the new genus to the extant family Tarsiidae as its only known fossil representative. Recovery of a Tarsius-like primate from Africa suggests that it or its ancestors might have been immigrants from Europe, may have been derived from an unknown Asian stock related to the ancestry of Tarsius, or may have originated in Africa. ?? 1985 Nature Publishing Group.

Nature↗
USGS1984

First record of marsupials (Metatheria: Polyprotodonta) from the Oligocene in Africa

Metatherian (marsupial) and eutherian (placental) mammals are end members of a complex, possibly common North American1-4 or, less likely, a South American5 stock that diverged before the early late Cretaceous and underwent separate adaptive radiations establishing them as the two dominant mammalian groups (subclass Theria). By the later Cretaceous, marsupials were well situated in North America3 and were also present in South America6. Their oldest occurrences in Antarctica (later Eocene 7) and Australia (Oligocene8) are artefacts of exceptionally poor fossil records of mammals on those continents and it is clear that the Metatheria must have been quite diverse in both areas (physically connected in pre-Eocene times9) very much earlier5,7. Marsupials probably did not reach Europe much before their earliest record there in the early Eocene10. The Metatheria have not been identified from Asia, nor until now from Africa. We now report the discovery of the first fossil remains of a didelphid marsupial in Oligocene rocks in North Africa. ?? 1984 Nature Publishing Group.

Nature↗