Leinkupal: a diplodocid that survived into the Cretaceous

Leinkupal laticauda matters because a small fossil sample changed the known time and place of diplodocid survival. The genus was described from the Early Cretaceous of Patagonia, long after the better-known Jurassic diplodocids of North America and Africa. Its bones are not a complete giant skeleton: the holotype is a tail vertebra, accompanied by several other vertebrae assigned to the same species. The evidence supports a younger South American diplodocid, while popular claims that it was the last one go beyond what a fragmentary record can establish.

Quick facts

Vertebrae from Bajada Colorada

The material was recovered from the Bajada Colorada Formation in Neuquén Province, Argentina. Gallina, Apesteguía, Haluza and Canale named Leinkupal laticauda in 2014. The holotype, MMCH-Pv 63-1, is an anterior caudal vertebra. Other specimens assigned as paratypes include cervical, dorsal and additional tail vertebrae. Their referral rests on anatomical comparison and collection context; the assemblage does not amount to one complete articulated skeleton.

The formation is dated to the Berriasian–Valanginian interval of the Early Cretaceous. That age makes the fossils a notable extension beyond the classic Jurassic record of Diplodocidae. It does not mean the family disappeared at the Jurassic–Cretaceous boundary elsewhere and then reappeared. The older idea of a global extinction at that boundary was a conclusion drawn from an incomplete record; Leinkupal supplies positive evidence that at least one diplodocid lineage persisted in South America.

A name built around a wide tail

The name Leinkupal combines Mapudungun words interpreted as ‘vanishing family’. Laticauda refers to the broad tail suggested by lateral extensions on the anterior caudal vertebrae. These extensions are directly observable anatomy. Their implications for the shape of the full tail are inferred, because no continuous tail series or complete skeleton is known.

Diplodocid tails were long and mechanically important, but the fossil evidence does not show how Leinkupal used its tail in a particular encounter. A broad vertebra cannot by itself prove a crack, display, defence or exact balance function. Such proposals require biomechanical analysis and comparison across the family, and remain separate from the descriptive fact that the preserved vertebrae have distinctive transverse processes.

A rare southern diplodocid

The 2014 authors regarded Leinkupal as the first unequivocal diplodocid from South America and one of the youngest known members of the family. The qualification matters. Fossil distributions are uneven, and isolated bones may not be diagnostic enough to assign to a family. A new well-dated specimen can alter both the geographic picture and the apparent last occurrence of a group.

Phylogenetic analysis placed Leinkupal among diplodocines and suggested a relationship with the African Tornieria. That result admits more than one historical explanation: diplodocids may have had a broad early distribution, or lineages may have dispersed between continents. A family tree does not by itself identify a route, date or land bridge. Those questions also depend on geological connections and the ages of fossils from multiple regions.

The later braincase: useful, but tentative

A partial braincase, MMCh-Pv-232, was described from the same formation in a 2022 neuroanatomical study and tentatively assigned to Leinkupal. Computed tomography allowed the authors to reconstruct parts of its inner ear and cranial endocast. They noted similarities to other diplodocids and discussed a relatively short lagena as evidence consistent with lower auditory sensitivity than in some compared sauropods.

Because the braincase is not the original holotype and its identification is tentative, it should not be treated as certain Leinkupal anatomy without qualification. The inner ear estimate is comparative evidence, not a recording of what the animal heard. This specimen expands the discussion if the referral is correct, but the main species diagnosis still rests on the vertebral material described in 2014.

What remains unknown

No complete skeleton supplies a dependable body length or mass. Estimates based on relatives can be useful illustrations, but uncertainty in proportions compounds when most of the animal is missing. The fossils also do not establish its diet in detail, herd structure, migration or how it interacted with other Bajada Colorada animals. Regional faunal lists combine discoveries from separate beds and collecting histories.

The secure conclusion is more interesting than an exaggerated superlative: diplodocids survived in South America into the Early Cretaceous, and Leinkupal is the best-supported named example. Future vertebrae, skull elements or associated skeletons could refine its anatomy and relationships. Until then, readers can place the evidence beside other sauropods in the dinosaur catalogue without turning ‘one of the youngest known’ into ‘the last one’.