Tetrapod Zoology

Tetrapod Zoology

Amphibians, reptiles, birds and mammals - living and extinct

Mystery big cat skulls from the Peruvian Amazon not so mysterious anymore


Skulls and accompanying life restorations of (A) the Peruvian 'Anomalous jaguar' and (B) 'Peruvian tiger'; image by Gustavo Sanchez.

Scientific projects are very often years in the making. Within the past few days, I’ve had a new paper appear in the open-access journal PeerJ. It’s co-written with Manabu Sakamoto, Peter Hocking and Gustavo Sanchez. Therein, we examine and, we think, resolve the previously vexing identity of two big cat skulls obtained in the Peruvian Amazon (Naish et al. 2014).

Long-time Tet Zoo readers with exceptionally good memories might recall the ver 2 article – pu­­­­­­blished way back in June 2007 – in which I asked that most vexing of questions: “Peter Hocking’s big cats: where are you now?”. As you’ll know if you recall that article, or if you know a reasonable amount about South American mammalogy or cryptozoology, back in 1996, Peruvian ornithologist Peter Hocking announced the procurement of two skulls belonging to pantherine cats, suggested by him to represent two of the ‘mystery’ cats said by local people to inhabit the forested highlands of Peru’s Pasco Province (Hocking 1996).

Illustration by Peter Visccher, depicting Peruvian cryptids. The primate is the 'Isnachi'. From Greenwell (1994).

Hocking – perhaps best known in the world of zoology for the several bird species he has to his name – has long been collecting anecdotes from indigenous Peruvians about mystery animals: animals that don’t seem to match those known to scientists and which might represent undiscovered taxa (Hocking 1992, 1996, Greenwell 1994). Among these is the so-called ‘striped tiger’, a reddish, jaguar-sized cat marked with white, unbranched stripes. Its paradoxical name results from the fact that ‘el tigre’ is the name used across much of South America for Panthera onca, the Jaguar. In other words, it’s meant to be a ‘Striped jaguar’. We opted to use the name ‘Peruvian tiger’ for this alleged animal. Then there’s a second, Jaguar-like big cat, said to have solid black irregular spots, not rosettes like a Jaguar. We use the term ‘Anomalous jaguar’ for this animal. The adjacent illustration by Peter Visccher – produced to accompany an article by the late cryptozoologist Richard Greenwell – shows the Peruvian tiger and Anomalous jaguar together with a few other Peruvian mystery animals reported by Hocking (Greenwell 1994), though the illustration errs in giving the ‘Peruvian tiger’ dark stripes rather than white ones. The big black cat included in the scene is the ‘Yana puma’, an animal that might not be a cat after all, but a local name for the Spectacled bear Tremarctos ornatus.

Old news now is that Hocking managed to get hold of skulls said to belong to both the ‘Peruvian tiger’ and ‘Anomalous jaguar’. Preliminary observations on the anatomy and proportions of these skulls indicated that both were different from those of Jaguars.

'Peruvian tiger' (at left) and 'Anomalous jaguar' skulls in anterior view (and pretty much to scale). Photos by Peter Hocking.

In view of the possible significance of these animals (are we really talking about the possible existence of new living species or subspecies or, at least, local variants or morphs of big cat?), the discovery of actual, physical remains was pretty exciting. Alas, while these skulls were figured and briefly discussed on a couple of occasions (Hocking 1996, Bille 1997), a detailed or proper analysis never appeared, hence my 2007 Tet Zoo article. What was happening to these specimens? Well, nothing.

At top: a box from Peru, containing replica cat skulls. Exciting! At bottom: damage incurred to the 'Peruvian tiger' skull during transport. Unfortunate, but fixed by Gustavo.

A plan was formulated. It turned out that correspondent and Tet Zoo reader Gustavo Sanchez of Fundación Neotrópico in Tenerife knew Peter Hocking and was in correspondence with him. Peter was still in possession of the skulls and would make plaster replicas and send them to Europe. A collaboration was born. Gus received the replicas in November 2009 (unfortunately, they were substantially damaged during transit and repair was required). I, in turn, was very excited to receive them in February 2010. As you can see from the photos here, Peter is obviously a master at making amazingly good plaster replicas of skulls.

Work could begin, and I now brought in Manabu Sakamoto (then of the University of Bristol), the aim being to take measurements from the skulls and incorporate these into the large set of cat skull data that Manabu had been building up for other projects (see Sakamoto & Ruta 2012). Manabu and I did this work back in February 2011. This explains why photos of Manabu and myself, holding plaster replicas of big cat skulls, featured on Tet Zoo back in January 2012.

One of our several scatterplots. This one (showing the first and third linear discriminants plotted against each other) shows both Peruvian skulls plotting at the edge of the Jaguar cloud. Image from Naish et al. (2014).

36 cranial and 13 mandibular measurements were taken from both skulls. These were then subjected to linear discriminant analysis (LDA), a statistical technique that unites variables as linear combinations for the purposes of comparison and discrimination. Scatterplots were generated to see how linear discriminants calculated for the Peruvian skulls compared to those of other cats. Both skulls were unquestionably close to Leopard P. pardus and Jaguar, though they grouped separately from both species, closer to Leopard, and closer to Jaguar, respectively, in different analyses. However, by far the most robust results placed them close to the Jaguar cloud. Admittedly, they were at the edge of Jaguar morphospace, and the results from the analyses of the mandibular dataset were not particularly strong (Naish et al. 2014).

Both skulls looked to be those of Jaguars in any case: they have the obviously robust rostrum and dentition typical of this species as well as the broad coronoid process, concave dorsal surface to the nasals, and concave, flexed surface to the dorsolateral part of the maxilla (Naish et al. 2014). It should also be added that the skulls possess characters typical of Panthera, and typical of the Panthera clade that includes all species except the Snow leopard P. uncia (Naish et al. 2014).

(A) 'Anomalous jaguar and (B) 'Peruvian tiger' skulls in oblique dorsolateral view to show the flexed, concave dorsolateral part of the maxilla present in both specimens. Photo by Barry Marsh, from Naish et al. (2014).

The conclusion has to be that both skulls are of Jaguars after all, in which case the unusual coat colours and patterns reported for these individuals represent genetic anomalies of the sort already well known among wild cats. Abnormalities of just about every conceivable sort are on record as it is: Leopards and Cheetahs with stripes or pseudo-stripes are known, for example, rendering it plausible that reports of striped ‘Peruvian tigers’ refer to sightings of weird, aberrant Jaguars. Alternatively, it’s possible that the ‘Peruvian tiger’ skull didn’t really belong together with the striped pelt it was reportedly in original association with. We can’t explore this possibility any further since that pelt (and any other remains) were sold to an unknown party (Naish et al. 2014). If you’re wondering about DNA retrieval... given that the original skulls were defleshed and then boiled by the hunters who obtained them, we opted not to attempt DNA analysis. We do recognise, of course, that this might still be do-able.

A tangent on the backstory

Manabu, hard at work measuring cat skulls in 2011. Image by Darren Naish.

The plan throughout this project is that we’d have a publishable paper, whatever the results. If the skulls really did represent one or two new taxa: that’s great – publication! But if the skulls could be identified as belonging to a known taxon: that’s great – publication! And let us not forget that there’s been a reasonable amount of interest in the outcome of this specific case.

As those of you who are publishing scientists will well know, part of the challenge of doing science comes not just from doing the science itself, but from getting your research published. Finding a ‘home’ for a given manuscript can be hard, and the ideas, recommendations and criticisms of editors and reviewers can be difficult or even utterly impossible to take account of. A specific problem we had with this manuscript is that some parties didn’t consider that it examined a hypothesis worth testing. One editor turned down the manuscript because they said that it “lacked a scientific rationale”, their thinking apparently being that, since there isn’t an active controversy over the number of living Panthera species in South America, the project is redundant and not worthy of publication. I disagree emphatically with this perspective – there’s definitely a mystery here worth analysing – and I thus ended up wasting weeks of time fighting with editors and corresponding with people higher up the chain of command. While people at the journal concerned did eventually change their mind and say that they were prepared to reconsider the manuscript, I had to give up on them because I just couldn’t find the time to meet their demands for resubmission. Horror stories like this abound in academic publishing. Remember that I do academic research ‘in spare time’ and am not paid to do it.

Lest we forget how awesome Jaguars are, here's one of several images from a sequence in which a Brazilian Jaguar swims across a river to ambush, catch and kill a large caiman. Image by Justin Black, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

Here’s where PeerJ comes in. PeerJ is a recently launched, open-access, peer-reviewed online journal, its stated mission being to “help the world efficiently publish its knowledge”. A really painful part of the academic process concerns formatting. Every time you submit a manuscript to a journal, you’re expected to comply specifically to its style. And, seeing as virtually every single journal has its own style (in terms of how works are cited, how references are written, how figures are designed, and so on), many, most or all of us have wasted pointless, painful hours or days of our lives reformatting journal articles (this despite the fact that all technical journals have their own editorial staff and are typically owned by publishing companies anyway!). [Adjacent image by Justin Black.]

PeerJ is special in that it doesn’t have its own style – it merely demands that your manuscript is scientifically valid, novel and conforms to usual scientific protocol. This is a major plus-point: no painful reformatting required if your manuscript was previously designed with another journal in mind. To publish there, you do have to pay a $99 lifetime membership fee. Without getting into the finer points of my academic finances, let’s just say that I owe huge thanks to my excellent friends Mike P. Taylor and Matt Wedel of SV-POW! for paying for my subscription as a birthday present.

It took some years, but we got there in the end. Naish (left) and Sakamoto with replica pantherine skulls.

Anyway, the manuscript ended up in PeerJ. So, it only took me four years to get the research done and the paper published. That’s not great, but it’s not all that bad either, all things considered. I’m really pleased with everything about the experience of publishing with PeerJ and will definitely be submitting work there again. I should add that I really wanted this research to appear in an open-access journal since I think it's important that it's available to interested parties in Peru, not locked up behind a subscription paywall.

I think we can now say with confidence that those two skulls are those of Jaguars after all. Does this resolve the whole enigma of ‘Peruvian tigers’ and ‘Anomalous jaguars’? That question is harder to answer, and as usual we wait for good additional data before we can proceed further. And I’ll end by saying that there are other pieces of ‘mystery cat’ evidence out there that could also do with being analysed in the peer-reviewed technical literature...

For previous Tet Zoo articles on cats and other carnivorans, see...

Refs - -

Bille, M. 1997. News and comment. Exotic Zoology 4 (2), 4.

Greenwell, J. R. 1994. Mean mammals of the mountains. BBC Wildlife 12 (6), 33.

Hocking, P. J. 1992. Large Peruvian mammals unknown to zoology. Cryptozoology 11, 38-50.

- . 1996. Further investigations into unknown Peruvian mammals. Cryptozoology 12, 50-57.

Naish, D., Sakamoto, M., Hocking, P. & Sanchez, G. 2014. ‘Mystery big cats’ in the Peruvian Amazon: morphometrics solve a cryptozoological mystery. PeerJ 2:e291; DOI 10.7717/peerj.291

Sakamoto, M. & Ruta, M. 2012. Convergence and divergence in the evolution of cat skulls: temporal and spatial patterns of morphological diversity. PLoS ONE 7:e39752 DOI 10.1371/journal.pone.0039752

The views expressed are those of the author and are not necessarily those of Scientific American.

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