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6 - Necromantis Weithofer, 1887, large carnivorous Middle and Late Eocene bats from the French Quercy Phosphorites: new data and unresolved relationships
- Edited by Gregg F. Gunnell, Duke University, North Carolina, Nancy B. Simmons, American Museum of Natural History, New York
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- Book:
- Evolutionary History of Bats
- Published online:
- 05 June 2012
- Print publication:
- 29 March 2012, pp 210-251
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Summary
Introduction
In 1887, Weithofer described the fossil bat Necromantis adichaster on the basis of fragmentary material from the Paleogene Quercy phosphorite fillings of southwestern France. The Phosphorites are composed mostly of phosphate-rich clays, including fossil materials, that fill the caves and fissures riddling the karstic landscape in the large regional Quercy area (including parts of four departments, but mostly the Lot and Tarn-et-Garonne) and extending west to the hills of the Massif Central (e.g., Thévenin, 1903; Gèze, 1938). The fillings were deposited over a period of about 30 million years from the late Early Eocene to the late Early Miocene (e.g., Legendre et al., 1997), but also as recently as the Late Pliocene and Quaternary (Crochet et al., 2006; Aguilar et al., 2007).
From 1870 to 1907, many mines were established in the Quercy region to exploit the naturally occurring phosphate, a widely used fertilizer, with much of the Quercy ore being exported (see Durand-Delga, 2006 for a detailed history of the Quercy mining operations). Geologists were rarely allowed to visit the localities during the mining period, with fortunate exceptions, including Trutat, who took photographs (see Duranthon and Ripoll, 2006), and Thévenin, who produced a learned report (Thévenin, 1903). During the c. 40 years of intensive mining, the Quercy Phosphorites became renowned for producing many fossil bones and teeth, in good and even exceptional condition (Daubrée, 1871; Delfortrie, 1872). Today the Quercy Phosphorites are globally recognized for the thousands of vertebrate fossils they have produced, including many specimens of bats. For a recently updated record of Quercy micromammals see Sigé and Hugueney (2006) and for a catalog of classic Quercy mammalian taxa (i.e., before more recent excavations) see Sigé et al. (1979).
3 - Shoulder joint and inner ear of Tachypteron franzeni, an emballonurid bat from the Middle Eocene of Messel
- Edited by Gregg F. Gunnell, Duke University, North Carolina, Nancy B. Simmons, American Museum of Natural History, New York
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- Book:
- Evolutionary History of Bats
- Published online:
- 05 June 2012
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- 29 March 2012, pp 67-104
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Summary
Introduction
Over 600 Middle Eocene bat specimens have been excavated from the Messel pit (Grube Messel, near Darmstadt, Germany), and seven species have been described thus far. Many of the fossils are preserved as complete skeletons, often with soft body outlines and gut contents. Six of the bat species represent three extinct families, whereas Tachypteron franzeni can be assigned to the extant family Emballonuridae (Storch et al., 2002). T. franzeni is known only from two specimens; however, these are extraordinarily well preserved, including the shoulder joints and inner ears, so this had already been recognized in the original description of T. franzeni, and these close resemblances to extant emballonurids led to the conclusion that T. franzeni had already evolved similar bioacoustic specializations and a similar flight style to modern taxa.
The shoulder joints of bats are sophisticated structures showing remarkable morphological variation. Miller's (1907) investigations on the differentiations of the shoulder within the Microchiroptera were continued by the studies of other authors (Vaughan, 1970; Strickler, 1978; Hermanson and Altenbach, 1983).
Three different types of shoulder joint can be distinguished within the Chiroptera: the primitive morphology of the shoulder joint with a globular humeral head and corresponding glenoid cavity, as seen in Megachiroptera and Rhinopomatidae; a derived shoulder joint with an oblong humeral head and a single trough-like articular surface on the scapula, found in members of the superfamilies Emballonuroidea, Rhinolophoidea and Noctilionoidea; a derived shoulder joint with a secondary articulation between the tuberculum majus and a secondary articular facet on the dorsal side of the scapula, as seen in the remaining families. Their distribution within the order gives evidence of parallel evolution of the derived types (Schlosser-Sturm and Schliemann, 1995). The morphological modifications of the derived joints are interpreted as a functional response to a biomechanical demand connected with flight (Norberg, 2002), i.e., to limit pronation of the humerus during the downstroke of the wing beat cycle, realized in two different mechanical ways (Schlosser-Sturm, 1982; Altenbach, 1987; Schliemann and Schlosser-Sturm, 1999). Because movement restriction was described for the primitive type as well (Bergemann, 2003), functional interpretations are still a matter of controversy.
13 - Necromantodonty, the primitive condition of lower molars among bats
- Edited by Gregg F. Gunnell, Duke University, North Carolina, Nancy B. Simmons, American Museum of Natural History, New York
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- Book:
- Evolutionary History of Bats
- Published online:
- 05 June 2012
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- 29 March 2012, pp 456-469
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Summary
Introduction
Two dominant structural types in the lower molars of insectivorous bats have been described and their evolutionary implications interpreted: these are known as the nyctalodont and myotodont conditions (Menu and Sigé, 1971). Although previously noted as differential characters by some authors (e.g., Lavocat, 1961), these structures had not been the subject of extensive study among bats. Since then, intermediate conditions, interpreted as transitional evolutionary steps between the two patterns, have been reported in natural populations of both living and fossil bats.
Among the oldest known bats, a different but characteristic pattern in the posterior structure of the lower molar is exhibited by various species, and is interpreted here to represent the primitive condition of chiropteran lower molars. It is the pattern displayed by the most archaic bats, notably within, but not restricted to, archaeonycterids, although not all of them. These archaic bats, known only as fossils, are reported from the Early Eocene of various and presently disjunct regions of the world. The condition is less commonly displayed by younger, more derived and taxonomically diverse fossil bats. The classic fossil bat genus Necromantis Weithofer, 1887, now more accurately dated as Middle to Late Eocene in age (Maitre et al., 2007; Maitre, 2008; Hand et al., Chapter 6, this volume), well exemplifies this archaic lower molar structure, and the name necromantodonty is used here to typify it.
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