Titanis
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Skeletal reconstruction of Titanis |
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| Pliocene , Old Pleistocene | ||||||||||||
| 5.3 to 1.8 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Titanis | ||||||||||||
| Brodkorb , 1963 | ||||||||||||
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Titanis is a genus of the extinct family of Phorusrhacidae ("terror birds") thatlivedin North America in the Pliocene 5 to 2 million years ago. She is considered to be one of the youngest known representatives of the bird group. The finds, most of which came from Florida and Texas , are sparse and mostly preserved in a fragmented state. Statements on body size and weight are therefore only possible to a limited extent, but in general Titanis may have resembled the other "terror birds". The genus received its scientific name in 1963.
features
Titanis is one of the larger representatives of the Phorusrhacidae . The bird genus, however, is only known through highly fragmented bone material, which includes a little more than three dozen pieces. During the initial description , Titanis was estimated to be about the same size as Phorusrhacos , but smaller than Devincenzia . Since there are hardly any completely preserved bones, the size determinations are imprecise. A study of the entire find material, which was published in 2005, assumes a peak height of about 1.44 to 1.87 m. The scientists note, however, that the values may be set too low due to the fragmentary character of the find and that the animals may well have reached the total height of 2.4 m determined for Phorusrhacos . An originally assumed weight of 150 kg was not confirmed, on the contrary, according to the study, the found material does not allow an exact weight specification. In general, Titanis was probably very similar to its South American relatives with a narrow body, clearly elongated legs and strongly receded wings .
The find material has so far only been partially described in detail. Among other things, the Os quadratojugale of the skull has been handed down several times, the largest specimen has a preserved length of 17 cm and a height of 2.3 cm. In comparison with other members of the Phorusrhacidae, the skull could have been between 36 and 54 cm long. The wing leg measured 7.5 cm in length and 1.5 cm in width. It had large joint facets on the sides that connected it to the sphenoid bone . The relative size of the bone and the shape and position of the articular surfaces correspond to the other Phorusrhaciden. The extremely reduced wing bones compared to the hind legs are noticeable, which is generally typical of flightless birds. However, they are even more regressed in Titanis and in terms of body size are the shortest within the Phorusrhacidae. The arm reached only one sixth of the total length of the leg, with Psilopterus it is a third. The humerus showed a robust construction and a laterally pressed shaft. The inside was not completely hollow, but rather interspersed with a network of bones. The Carpometacarpus was short and strong, its size was about that of a turkey . A ball-like joint at the front end was interpreted as the attachment point for a claw on the first finger beam. Since joint formations of this type also occur in today's Seriemas , the closest relatives of the Phorusrhacidae, in which no claw is formed, this interpretation is questioned. The tarsometatarsus was robust, the lower joint end was 7.6 cm wide. The middle of the three articulated rollers had the largest dimensions, in contrast to Phorusrhacos it widened slightly at the end, moreover it was perpendicular to the shaft and was not inclined slightly forward as with the latter. The inner and outer articulated rollers were significantly smaller, their width was only about half of the middle ones, making them narrower than Devincenzia's . The general structure of the bone indicates that the middle of the three forward-facing toes was clearly the strongest. The first phalanx had a proximally higher joint than another. The last phalange measured up to 6 cm in length and was markedly curved and pointed at the front, which indicates the presence of strong claws.
Fossil finds
With the emergence of the Isthmus of Panama and the formation of a land bridge between North and South America , the Phorusrhacidae also spread to the north in the course of the Great American Fauna Exchange . However, Titanis is the only proven representative of this group of birds in North America, and the find material is relatively sparse and mostly heavily fragmented. The largest part, around 40 fragments, comes from Florida and was collected between the 1960s and 1990s. The material is distributed over three sites: the deposits of the Santa Fe River in the north, a karst funnel near Inglis in the northwest and a so far single bone from Port Charlotte in the central part of the US state. The fossil remains are limited to a few skull fragments along with the lower jaw, vertebrae, and parts of the fore and hind limbs. Of the latter, only the carpometacarpus and various phalanxes of the third and fourth ray are completely preserved. So far only a single phalange of the right foot has been documented from Texas . The find came to light while working in a gravel works in San Patricio County , which extracts gravel material from the lowest terrace of the Nueces River below the waterline. From a geological point of view, there is a large time span for age dating for both find regions, ranging from the Lower Pliocene to the end of the Pleistocene , which is mostly due to the conditions of the find. The mammalian fauna found around cannot give any exact biostratigraphic clues due to the mixture of the material . Investigations of the rare earths stored in the bones , however, showed the age of the Lower Pliocene for the find from Texas about 5 million years ago and for the finds from North Florida to the transition from the Pliocene to the Pleistocene about 2.2 to 1.8 million years ago restrict. Titanis is one of the early immigrants during the Great American Fauna Exchange.
In 2013, an anterior fragment of the upper beak approximately 9.1 cm long and 5.5 cm high was referred to Titanis from the lower portions of the Olla Formation in Anza-Borrego Desert State Park in southern California . The find had already been discovered in 1961, but had previously been placed in Teratornis or Aiolornis . The find layer is dated radiometrically to about 3.7 million years, which corresponds with the age values of the other finds from Titanis . Morphologically and structurally, the fossil record resembles those of the well-known Phorus Rhacids. It thus extends the area of discovery of Titanis considerably further west.
Paleobiology
The sites of the fossil remains found so far suggest that Titanis was adapted to open landscapes that were associated with karst phenomena and springs. It is possible that the birds were opportunistic hunters who preferred small prey. Overall, based on the few previous evidence , Titanis appeared rather rarely. Based on the different sizes of the os quadratojugale in adult individuals, it may be possible to infer a sexual dimorphism .
Systematics
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Internal systematics of the Phorusrhacidae according to Degrange et al. 2015
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Titanis is a genus from the Phorusrhacidae family, which is now extinct . These include medium-sized to large, ground-based birds that feed mainly on predatory food, which is indicated by a pointed end of the beak running downwards in an arc and claws shaped like birds of prey . Because of this, the Phorusrhacidae are often colloquially referred to as "terror birds". They are closely related to today's Seriemas , who inhabit the open landscapes of South America . The origin of the Phorusrhacidae is also suspected on this continent, but Titanis was the only known representative to reach North America . The family occurred from the Upper Oligocene to the late Pleistocene , the latest known finds come from Uruguay.
Originally Titanis was placed in the subfamily of the Phorusrhacinae and formed a closer relatives group with the huge Kelenken , the not so large Devincenzia and Phorusrhacos , the type form of the entire family. The representatives of the subfamily were characterized by a large, but relatively slender physique and well-developed legs, with the long, extended metatarsus reaching at least 60% of the length of the tibiotarsus , which suggests nimble locomotion. Another characteristic was the elongated and narrow symphysis of the lower jaw. Investigations on the tribal history of the Phorusrhacidae from 2015 showed that the Phorusrhacinae are polyphyletic and together with the other subfamilies of the Physornithinae and the Patagornithinae form a common group. This largely includes the large forms of the family and is therefore temporarily referred to as "real terror birds". It is in turn opposed to a group of rather small-stature representatives, which is composed of the subfamilies of the Psilopterinae and the Mesembriornithinae and also carries the temporary term "Psilopterines".
The genus Titanis was first scientifically described in 1963 by Pierce Brodkorb . The holotype (copy number UF-4108 ) is a fragmented tarsometatarsus, of which only the distal, lower joint end has been preserved. This was discovered together with a toe in the winter of 1961/62 by Benjamin I. Waller in deposits of the Santa Fe River in Columbia County in northern Florida . In honor of the finder, Brodkorb named the only known species Titanis walleri . The generic name is borrowed from Greek mythology ( τιτανις Titanis ) and designates a single goddess from the race of the Titans .
literature
- Gina C. Gould and Irvy R. Quitmyer: Titanis walleri: bones of contention. Bulletin of the Florida Museum of Natural History 45, 2005, pp. 201-229.
Individual evidence
- ↑ a b c Pierce Brodkorb: A giant flightless bird from the Pleistocene of Florida. The Auk 80 (2), 1963, pp. 111-115.
- ^ A b Jon A. Baskin: The giant flightless bird Titanis walleri (Aves: Phorusrhacidae) from the Pleistocene coastal plain of South Texas. Journal of Vertebrate Paleontology 15 (4), 1995, pp. 842-844.
- ↑ a b c d Gina C. Gould and Irvy R. Quitmyer: Titanis walleri: bones of contention. Bulletin of the Florida Museum of Natural History 45, 2005, pp. 201-229. ( [1] )
- ^ A b c Robert M. Chandler: The wing of Titanis walleri (Aves: Phorusrhacidae) from the Late Blancan of Florida. Bulletin of the Florida Museum of Natural History, Biological Sciences 36, 1994, pp. 175-180.
- ↑ Bruce J. McFadden, Joann Labs-Hochstein, Richard C. Hulbert Jr. and Jon A. Baskin: Revised age of the late Neogene terror bird (Titanis) in North America during the Great American Interchange. Geology 35 (2), 2007, pp. 123-126.
- ↑ Hildegarde Howard: The Incredible Teratorn Agai. The Condor 74 (3), 1972, pp. 341-344.
- ^ Robert M. Chandler, George T. Jefferson, Lowell Lindsay, and Susan P. Vescera: The terror bird, Titanis (Phorusrhacidae), from Pliocene Olla Formation, Anza-Borrego Desert State Park, southern California. In: Robert E. Reynolds (Ed.): Raising Questions in the Central Mojave Desert. California State University Desert Studies Center, 2013, pp. 181-183.
- ↑ a b Herculano MF Alvarenga and Elizabeth Höfling: Systematic revision of the Phorusrhacidae (Aves: Ralliformes). Papéis Avulsos de Zoologia 43 (4), 2003, pp. 55-91. ( [2] )
- ↑ a b c Federico J. Degrange, Claudia P. Tambussi, Matías L. Taglioretti, Alejandro Dondas and Fernando Scaglia: A New Mesembriornithinae (Aves, Phorusrhacidae) Provides New Insights Into the Phylogeny and Sensory Capabilities of Terror Birds. Journal of Vertebrate Paleontology 35 (2), 2015 doi: 10.1080 / 02724634.2014.912656 .
- ↑ Herculano Alvarenga, Washington Jones and Andrés Rinderknecht: The youngest record of phorusrhacid birds (Aves, Phorusrhacidae) from the late Pleistocene of Uruguay. New Yearbook for Geology and Paleontology Abhandlungen 256 (2), 2010, pp. 229–234.
- ^ Herculano MF Alvarenga, Luis M. Chiappe and Sara Bertelli: The terrorbirds. In: Gareth Dyke and Gary Kaiser (Eds.): Living Dinosaurs: The Evolutionary History of Modern Birds. Wiley-Blackwell, Chichester, UK, 2011, pp. 187-208.
Web links
- Portrait of Titanis the Florida Museum of Natural History (English)
- Portrait of Titanis (Spanish)