Pamparaptor

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Pamparaptor
Temporal range: Late Cretaceous,[1]
~93.5-85.5 Ma — Late Turonian
Life restoration
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Paraves
Family: Dromaeosauridae
Genus: Pamparaptor
Porfiri, Calvo & Santos, 2011
Type species
Pamparaptor micros
Porfiri, Calvo & Santos, 2011

Pamparaptor (

Greek word for “small”), which is known from a single specimen consisting of a mostly complete and fully-articulated left foot, which preserves the iconic dromaeosaur-like “killing claw”.[2]

Discovery

The type and only specimen of Pamparaptor was discovered in 2005 by a technician named Diego Rosales who was working for the Lake Barreales Paleontological Center (or CePaLB) at the National University of Comahue.[2] It was found at a locality called the “Baal Quarry”, which is an outcrop of the Portezuelo Formation dated to the late Turonian or early Coniacian.[1] The locality is on the northern shore of Lake Barreales Lake and about 90 kilometres (56 mi) northwest of the city of Neuquén.[2]

The specimen was reposited at the National University of Comahue and was given the designation MUCPv-1163. It consists of all three

phalanges each from the third and fourth toes from the left foot of the same animal. These elements were discovered in articulation with one another and so they can be reasonably inferred to have been from the same animal.[2]

The holotype specimen of Pamparaptor was first reported in the literature in 2007 by the same researchers who would later go on to describe it. The specimen bore some similarities to the contemporaneous taxon Neuquenraptor, but was much smaller. For those reasons, MUCPv-1163 was believed to be a juvenile or subadult specimen of Neuquenraptor.[3]

Pamparaptor was finally described as a new genus in a publication of the Annals of the Brazilian Academy of Sciences in 2010 by a team of researchers including Juan Porfiri, Jorge Calvo, and Domenica Dos Santos. The authors remarked in the paper that their description is brief, but explained that they are confident that the remains cannot belong to any pre-existing taxon known from the Portezuelo Formation.[2]

Description

Pamparaptor was a small

metatarsal (the longest bone in the foot) is only about 9.3 centimetres (3.7 in). The specimen is highly incomplete, but Porfiri and colleagues used the size of the foot to estimate that the animal would have been between 0.5 metres (1.6 ft) and 0.7 metres (2.3 ft) long in life. They did not give an estimate of the animal’s mass.[2] Rubén Molina-Pérez and Asier Larramendi gave a slightly greater length estimate of about 1.15 metres (3.8 ft) long and they also gave a weight estimate of 2.6 kilograms (5.7 lb) in weight.[4]

In their description of Pamparaptor, Porfiri and colleagues diagnose the genus as distinct from all other deinonychosaurs by the following

phalanges of the second toe, and a small sulcus on the distal end of the second metatarsal.[2]

Classification

The anatomically similar unenlagiine Neuquenraptor

The discovery of Pamparaptor was originally reported in 2007 at a conference of the 23rd Argentine Conference of Vertebrate Paleontology by the same authors who would later describe it.

metatarsals, a large ridge on the lateral side of the second toe-claw, and a lateral expansion of the third metatarsal, which was believed to be an autapomorphy of Neuquenraptor.[3]

Pamparaptor is now believed to represent its own genus and has been distinguished from Neuquenraptor by the lack of a significant difference in the ratio between the sizes of the

unenlagiine dromaeosaurid.[2]

Possible

In their description of the taxon, Porfiri and colleagues did not conduct a phylogenetic analysis. They stated that the incomplete nature of the holotype combined with the overall scarcity of

deinonychosaur fossils in Gondwana mean that any such analyses are likely to be highly incomplete. However, they do suggest that the discovery of aberrant taxa like Pamparaptor provide clues for the existence of an endemic lineage of dromaeosaurs distinct from the unenlagiines.[2]

In 2018, Federico A. Gianechini, Peter J. Makovicky, Sebastián Apesteguía, and Ignacio Cerda published an osteological description of all remains referred to the genus

monophyletic clades of maniraptorans. They elected to remove Pamparaptor, along with the problematic genera Kinnareemimus and Pyroraptor, from their final analysis, which resolved the consensus tree considerably. Therefore they do not make any concrete hypotheses regarding its phylogeny.[7] In 2020, Michael Pittman and Xu Xing published a review of pennaraptoran systematics in which they suggest that Pamparaptor has affinities with the unenlagiines, but they do not make any further remarks on its classification, and it is not included in any of the trees they present.[9]

Paleoecology

Pamparaptor is located in Argentina
Pamparaptor
Location of the Portezuelo Formation in Argentina

Paleoenvironment

The

Cretaceous period, this region was considerably further southeast than it is today.[1]

The Portezuelo Formation is primarily composed of yellow and red-brown

claystones and indicate the region contained an alluvial fan. This environment was eventually covered by paleosols, which mean that there was likely a long period of stability near the upper parts of the formation. The formation as a whole is about 95–130 metres (312–427 ft) thick, and was likely deposited over a period roughly from the late Turonian to the early Coniacian.[10]

Contemporary fauna

Relatively few non-

pleurodire lineages.[10] The remains of crocodyliformes have also been found, representing the named genus Patagosuchus and a second, unnamed notosuchian. However, the diversity of notosuchians in other Late Cretaceous formations of South America has led some researchers to suggest that there are more crocodyliformes that have yet to be discovered.[11] At least one species of fish is also known from the waterways of the Portezuelo Formation.[12]

The Baal Quarry locality is known for containing the holotype of Patagosuchus as well as the large

abelisauroids are known including one named form, Elemgasem, and at least two unnamed taxa.[15] Fragmentary bones of iguanodontians have also been recovered, but none of these have been formally described.[10]

See also

References

  1. ^ a b c d Carrano, Matthew (2008). "Baal Quarry, Lago Barreales [MUCP] (Cretaceous of Argentina)". The Paleobiology Database. Theropoda - Pamparaptor micros n. gen. n. sp., Porfiri et al. 2011, maniraptoran; MUCPv-1163, articulated left foot
  2. ^
    PMID 21437378
    .
  3. ^ a b c Porfiri, Calvo, dos Santos and Valieri, 2007. New record of Neuquenraptor (Theropoda, Dromaeosauridae) from the Late Cretaceous of Patagonia. Ameghiniana. 44(S), 34R.
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  10. ^ a b c d Leanza, H.A.; Apesteguia, S.; Novas, F.E.; De la Fuente, M.S. (2004). "Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages". Cretaceous Research. 25: 61–87. Retrieved 2019-02-16.
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  14. ^ Calvo, J.O.; Porfiri, J.D.; Kellner, A.W. (2004). "On a new maniraptoran dinosaur (Theropoda) from the Upper Cretaceous of Neuquén, Patagonia, Argentina". Arq. Mus. Nacional. Rio de Janeiro. 62: 549–566.
  15. .