Fettschwalme (family)
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Fettschwalm ( Steatornis caripensis ) |
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| Steatornithidae | ||||||||||
| Bonaparte , 1842 |
The fat swallows (Steatornithidae) are a family of birds from the order of the swallow-like (Caprimulgiformes). They include the recent fat swallow ( Steatornis caripensis ) and the fossil species Prefica nivea from the Eocene .
features
Fat swallows differ from other Schwalm-like families by their hard, curved and powerful bill, which has a small subterminal tooth. The rostrum is flexibly connected to the skull. The ploughshare is curved inward; the two halves of the palatine bone meet in the middle of the ploughshare bone . The tarsometatarsus is significantly shortened and is only about half as long as the middle toe in the fat swallow .
nutrition
While the other swallow-like carnivores feed on, the recent fat swallow eats fruits, for example from laurel plants , palm plants or balsam trees ; its beak is adapted to this diet. The pulp is digested, the seeds are then excreted, with which the fat swallow acts as a vector for the spread of the trees. The fossil species Prefica nivea shows the same beak structure. In the same layer as their holotype there are fossils of the same families and, in some cases, even genera of plants, the fruits of which the swallow eats in today's South America, which indicates a common diet.
Systematics and history of development
External system
The fat swallows are basal in the order of the swallow-like. Due to their morphological and ecological peculiarities, they represent a relatively isolated group and are - depending on the author - either placed in their own suborder Steatornithes or a superfamily Steathornithoidea. Their sister taxons are all of today's Schwalm-like, which probably split off from them before the early Eocene. The relationships within the Caprimulgiformes are shown in the following cladogram.
| Swallow-like (Caprimulgiformes) |
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Internal system
The fat swallows are divided into two subfamilies: The Preficinae with Prefica nivea as the only species on the one hand and the monotypical Steatornithinae with the fat swallow on the other.
Subfamily Preficinae: Primitive fat swallows with weakly differentiated legs and relatively thin humerus bones
Subfamily Steathorninae: Modern fat swallows with a highly specialized running and flying apparatus that is adapted to the cave environment.
- Oilbird ( Steathornis caripensis )
The assignment of some fossils such as Prefica nivea from the early Eocene and found in the North American Green River Formation ( Fluvioviridavis ) and the Messel Pit ( Eurofluvioviridavis ) is unclear . They show much in common with Precifica nivea , but do not have sufficiently differentiated characteristics to be able to assign them to a recent order of birds. But if they actually represent early forms of the fat swallow, today's fat swallow would be a relic species from a subordination that was once spread over several continents.
Evidence and references
literature
- David Thomas Holyoak: Nightjars and their Allies: The Caprimulgiformes. Oxford University Press, 2001. ISBN 0-19-854987-3 .
- Joseph del Hoyo, Andrew Elliot and Jordi Sargatal (Eds.): Handbook of the Birds of the World. Volume 5: Barn-owls to Hummingbirds. Lynx Edicions, 1999, ISBN 84-87334-25-3 .
- Gerald Mayr, Michael Daniels: A new short-legged landbird from the early Eocene of Wyoming and contemporaneous European sites. In: Acta Palaeontologica Polonica 43 (3), 2001, pp. 393-402. (Online as PDF )
- Storrs L. Olson: An early Eocene oilbird from the Green River formation of Wyoming (Caprimulfiformes: Steatornithidae). In: Documents des Laboratoires de Géologie de Lyon 99, 1987, pp. 57-69.
Web links
Individual evidence
- ↑ Holyoak 2001 , p. 95.
- ↑ Holyoak 2001 , p. 20.
- ↑ Del Hoyo et al. 1999 , p. 243.
- ↑ Olson 1987 , p. 59.
- ↑ Mayr & Daniels 2001 , p. 394.
- ↑ Del Hoyo et al. 1999 , p. 244.