Patagotitan
| Patagotitan | ||||||||||||
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Patagotitan |
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| Temporal occurrence | ||||||||||||
| " Middle Chalk " (Upper Albium to Lower Cenomanium ) | ||||||||||||
| 107.5 to 96.2 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Patagotitan | ||||||||||||
| Carballido, et al. , 2017 | ||||||||||||
Patagotitan is a genus of sauropod dinosaurs from the Titanosauria group . The only known species of the so far monotypical genus is Patagotitan mayorum from the uppermost Albium / lowest Cenomanium (approx. 107.5 to 96.2 million years ago) of Argentina.
Patagotitan is believed to be the largest known land animal of all time.
Etymology and find history
The generic name is made up of “Patago” for Patagonia and Greek Τιτάν , the titans from ancient Greek mythology. The additional species “ mayorum ” honors the Mayo family, on whose farm “La Flecha” the fossil remains were found and who also played a key role in the scientific recovery of the finds.
The first reports of the discovery of large fossil bones in the area of the “La Flecha” farm about 260 kilometers west of the city of Trelew in the Argentine province of Chubut come from the farm worker Aurelio Hernandez in 2010. His find was at the Museo Paleontológico Egidio Feruglio (MPEF) reported. Between 2012 and 2015, almost 130 bones from sauropods and 57 teeth from theropods ("predatory dinosaurs") were recovered as part of several excavation campaigns .
Fossil record
All known remains of Patagotitan come from the Cerro-Castaño- Member of the Cerro-Barcino Formation in the Somuncurá-Cañadón-Asfalto sedimentary basin of the Chubut Province . The partially volcanic-plastic sandstones of the Cerro Castaño Members were deposited in the uppermost Lower Cretaceous ( Albium ) in a sluggishly flowing meandering river system. The sauropod finds include the remains of at least six individuals from three horizons close to one another (FLV1-FLV3). The absolute-temporal (geochronological) uranium-lead dating of the zircons from the location of volcanic ash between the find horizons FLV1 and FLV2 revealed an age of 101.62 ± 0.18 million years.
The holotype MPEF-PV 3400 (FLV3) comprises two cervical vertebrae, eight vertebrae, more caudal vertebrae from the front portion of the tail, 3 Chevronknochen , a plurality of ribs, a shoulder blade and a coracoid (coracoid) both breast bone plates, both pubic bone and both femurs .
The Paratypus MPEF-PV 3399 (FLV1) comprises three vertebrae, a Elle (ulna) and spoke (radius), both pubic bone and both seat legs of the basin, a femur and a plurality of ribs partially preserved, neck and caudal vertebrae and Chevronknochen.
Join in:
- MPEF-PV 3372: a single tooth
- MPEF-PV 3375: a femur
- MPEF-PV 3390: Vertebral bodies of a cervical vertebra (FLV1)
- MPEF PV-3391 and 3392: 2 fibula fragments of different sizes (FLV1)
- MPEF-PV 3393: a tail vertebra (FLV1)
- MPEF-PV 3394: a thigh bone (FLV1)
- MPEF-PV 3395 and 3396: two humerus bones (FLV1)
- MPEF-PV 3397: one humerus (FLV2)
Patagotitan is one of the most fully known representatives of the Titanosauria .
Another excavation was carried out in the same stratigraphic location about 300 meters west of the original site (FLV4). The excavation revealed eight still connected caudal vertebrae (including the corresponding chevron bones) and two pubic bones of a similarly sized sauropod. However, the recovery of these finds has not yet been completed (as of 2017) and a clear connection with Patagotitan has not yet been confirmed.
Characteristics of the genus
Carballido et al., 2017 name several characteristic generic features :
- A triangular hyposphene exclusively on the third vertebra.
- The vertebral body of the first caudal vertebra is flat on the front, but strongly convex on the back.
- On the back of the spinous processes of the caudal vertebrae, a dichotomy is indicated.
- A straight edge on the lower outside of the thighbone (femur).
- A prominent bump on the back outside of the upper arm bone (humerus).
Patagotitan was probably up to 37 meters long and reached a body mass of up to 69 (± 17) tons. This made him one of the largest known sauropods . Histological examinations of the bone remnants indicate that the individuals found were adults , but the bone growth was not yet complete.
Age dating of the finds
With the uranium-lead dating method , only the age of formation of the zircons from the ash layer between the find horizons FLV1 and FLV2 can be determined and thus only the highest possible age of the ashes, because the dated zircons could have formed before the ashes were deposited, i.e. older be. Carballido et al., 2017 argue that the ascertained maximum age of the ash roughly corresponds to the age of the find horizons, although due to their stratigraphic position they must be a bit older (FLV1) or younger (FLV2 and FLV3) than the volcaniclastic horizon. The age of the ash layer falls in the uppermost albium . The authors emphasize, however, that the upper find horizons in particular can also be younger and cautiously indicate a find age between the upper Albian and the lower Cenomanian . A rough age estimate would accordingly be between approx. 107.5 million years (beginning of the uppermost Albian) and approx. Up to 96.2 million years (end of the lower Cenomanian).
According to the first authors, further attempts at dating to more precisely delimit the age of the find horizons are currently in progress.
Paleecology
The sediments of the Cerro Castaño Member of the Cerro Barcino Formation were deposited in the floodplain of a shallow, meandering river system. There are both sediments from the river channel itself and sediments from the floodplain. The Patagotitan finds come from the latter . Traces of root penetration in the sediments indicate that the meadow landscape was covered with vegetation.
The sedimentary structures of the find layers indicate that the flow energy of the deposit area was not high enough to transport individual bones or even entire carcasses of Patagotitan over significant distances. Likewise, no traces of unrolling due to such transport could be found on the bones found. The place of embedding is therefore to be roughly equated with the place of death. However, there are signs of different degrees of weathering of the bones of individual individuals, also within the individual horizons FLV1 - FLV3. This indicates that the bones of the individual individuals were exposed to atmospheric influences for different lengths of time before they were finally embedded in the sediment. At least one thigh bone (MPEF-PV 3394) shows signs of " dinoturbation ", ie it shows characteristic damage patterns that indicate that the bone has been trampled by other animals.
The three find horizons (FLV1 - FLV3) and the rock layers in between form an almost 2.5 m thick sediment sequence. From these findings it can be concluded that the site does not contain the remains of a single death, but that the site was regularly visited by Patagotitan mayorum over a longer period of time and that individual individuals perished there independently of one another.
In the horizons with larger, partially connected remains of Patagotitan mayorum , numerous teeth of theropods (“predatory dinosaurs”) could be recovered (31 teeth in the find horizon FLV1 and 26 teeth in the find horizon FLV3). The assumption that the carnivorous theropods ate the giant carcasses is obvious, but this is not supported by clear indications, e.g. B. Bite marks on the bones, proven.
Individual evidence
- ↑ a b c d e f g h i j k l m n J. L. Carballido, D. Pol, A. Otero, IA Cerda, L. Salgado, AC Garrido, J. Ramezani, NR Cúneo & JM Krause (2017): A. new giant titanosaur sheds light on body mass evolution amongst sauropod dinosaurs. In: Proceedings of the Royal Society B , Volume 284, Issue 1860, (Abstract)
- ↑ a b c R. P. Carmona, AM Umanzano & JM Krause: Estudio estratigráfico y sedimentológico de las sedimentitas portadoras de los titanosaurios gigantes del Albiano Tardío de Patagonia central, Argentina. In: Latin American Journal of Sedimentology and Basin Analysis , Volume 23, No. 2, pp. 127–132, 2016. (digitized version)
- ↑ Patagotitan mayorum, the largest dinosaur in the world - Found in Argentina - WORLD. Retrieved August 19, 2017 .
