Patagotitan

Credit: Mario Lanzas.

*Patagotitan* is an extinct genus of titanosaur that during the Late Cretaceous of Patagonia and Argentina.

## History

The lower thighbone of *Patagotitan* was first found in 2008 by Aurelio Hernández in the desert near La Flecha. Jose Luis Carballido and Diego Pol were partially funded by The Jurassic Foundation, where it was excavated. Between January 2013 and February 2015, expiditions into the site were carried out, finding more than 200 fossils. 57 theropod teeth were recovered and 6 partial *Patagotitan* with 130 bones, making the most complete titanosaur, recovered. It was named by José Luis Carballido, Diego Pol, Alejandro Otero, Ignacio Alejandro Cerda, Leonardo Salgado, Alberto Carlos Garrido, Jahandar Ramezani, Néstor Ruben Cúneo and Javier Marcelo Krause (2017), with the epithet after the Mayo family, who own the La Flecha ranch.

MPEF-PV 3400, the holotype found in the Latest Albian Cerro Barcino Formation, is a partial skeleton without the skull; 3 cervicals, 6 dorsals, 6 front caudals, 3 chevrons, ribs, breast bones, the right scapulocoracoid of the shoulder and both pubic bones and thighbones. This is the best preserved and has the most autapomorphies, with the other specimens designated paratypes. MPEF-PV 3399 is 6 cervicals, 4 dorsals, 1 front caudal, 16 rear caudals, ribs, chevrons, the left lower arm, ischia, the left pubic bone and the left thighbone. MPEF-PV 3372 is a tooth. MPEF-PV 3393 is a rear caudal. MPEF-PV 3395 and MPEF-PV 3396 are left humeri, with MPEF-PV 3397 as a right humerus. MPEF-PV 3375 is a left thighbone and MPEF-PV 3394 is the right thighbone. MPEF-PV 3391 and MPEF-PV3392 are 2 calfbones.

These did not all die at once. Within the sediment 343 centimeters thick, distinct, closely-spaced horizons represent three burial events due to individuals dying in floods. However, the flood water did not move them, only coating them in sandstone and mudstone. They all differ in no more than 5% in length, representing a monospecific assemblage.

## Description

—The describers
2014 news reports suggest a size of 40 meters (131 feet) and a weight of 77 tonnes (85 tons), however, science communicator Riley Black cautioned that same year that these may be uncertain. In 2017, it was formally named with a published length of 37 meters (121 feet) and a weight of 69 tonnes (76 tons) (using an equation) or 44.2–77.6 tonnes (43.5–76.4 long tons; 48.7–85.5 short tons) (volumetric skeletal models). In 2019, G.S. Paul suggests a length of 31 meters (102 feet) and 50-55 tonnes (49–54 long tons; 55–61 short tons) using volumetric models, being larger than his *Argentinosaurus* estimate. A revised scaling equation finds a mean estimate of 57 tonnes (56 long tons; 63 short tons) with a margin of error of 42.6-71.4 tonnes (41.8–70.3 long tons; 46.8–78.7 short tons), which is close to the 55 tonne volumetric estimate. The humerus is 1.675 meters (5.5 feet), which is smaller than other giant titanosaurs (such as *Notocolossus* and *Paralititan*). The femur is 2.38 meters (7.8 feet) long, making it one of the largest, aside from MLP-DP 46-VIII-21-3. The articulated dorsal series is smaller than *Argentinosaurus*. Black and Matt Wedel continued caution after publication, with Wedel noted in a blog post that it was on-par with known titanosaurs. However, all measurements were still larger than *Argentinosaurus*. Wedel also criticized their mass estimation. Other studies suggest a weight of 65–96.4 tonnes (71.7–106.3 tons).

Autapomorphies outlined are: the first 3 dorsals having a lamina prezygodiapophysealis that is vertical due to a higher articular process, a bulging underside on a ridge that runs through the side of the neural spine in the first 2 dorsals, the middle and rear dorsals having vertical neural spines; the first caudal having a centrum with a flat articulation facet in the front and a convex facet in the rear, the front caudal having a transverse width 4-6x larger than their front-rear length on the neural spines, the front caudal having neural spines with some bifurcation, a distinct bulge on the rear outer side of the upper arm and a lower thighbone with a straight outer edge.

## Classification

In 2017, it was placed into Longnkosauria, Eutitanosauria and Titanosauria as sister to *Argentinosaurus*. This suggests that multiple clades within Titanosauria independently acquired a large body size, one of the such taking place at the base of the *Notocolossus* + Lognkosauria clade, tripling from a maximum of 20 tonnes to a maximum of 60 tonnes.

## Paleoecology

It lived 102-95 million years ago during the Late Cretaceous in a forested region. Bearing sediments suggest that sedimentation occurred, indicating meandering floodplains.

## Notable Specimens

* "Máximo": A specimen housed at the Field Museum, with its name meaning "maximum" or "most" in Spanish. It is 122 feet long and 28 tall. The exhibit was carefully moved from Patagonia to the Field Museum where it was unloaded and assembled. The exhibit is in English and Spanish, and is included with the basic admission fee. As part of the marketing, one can "message" the specimen by using 1 (844) 994-3466 and ask him questions about *Patagotitan* and the Cretaceous. The Field Museum also set up #HelloMáximo for marketing.

## References

* https://en.wikipedia.org/wiki/Patagotitan
* https://www.fieldmuseum.org/exhibitions/maximo-titanosaur
* https://www.fieldmuseum.org/blog/making-maximo-titanosaur