The Matamata is an incredible animal. A morphologically bizarre, highly cryptic, aquatic South American turtle, it’s equipped with a super-specialised wide, flattened skull and a host of peculiar features that allow it to engulf fish and other prey in deft acts of rapid suction.
Surprisingly large (up to 1 m long), it has a very long, thick neck, and a proboscis that it uses as a snorkel. But of course you already know all of this because I covered it in depth in a series of articles published here during 2010 (if you need a refresher, see the links given below). My aim in this fifth and final article is to wrap up the matamata series and basically cover all the stuff I haven’t so far. Believe me, some of it is very neat…
We start with some nomenclatural and taxonomic stuff (don’t worry, it’s brief). First of all, what is the scientific name for the Matamata? Throughout these articles I’ve been using Chelus fimbriatus, as have many previous authors. Alas, as argued by Cadena et al. (2008), this is – shock horror – incorrect. Well, it’s incorrectly formatted, anyway.
The generic name Chelus is apparently feminine; ergo, any species names attached to it have to be feminine too. Chelus fimbriatus should thus really be Chelus fimbriata. One of the fossil matamatas (read on) also needs a name change: while often called Chelus columbianus, it should really be Chelus columbiana. As Cadeno et al. (2008) note, a few authors (Eugene Gaffney among them) have been aware of this and have been using the names correctly, but most haven’t. It seems that Cadena et al. (2008) are correct, so I’ll make an effort to use the correct species names from hereon (I did note the use of fimbriata previously, but said that it was incorrect. Oops). Thanks to Mark Hollowell for bringing this to my attention.
How many modern matamatas?
Moving on, you’ll have noticed in the preceding matamata articles that I’ve treated all modern matamata populations as belonging to the single species C. fimbriata. This is the generally held opinion – that is, that there’s but a single species. But is there? Actually, a substantial amount of morphological variation is observed between the matamatas of the Amazon and those of the Orinoco.
In a study devoted to this variation, Sánchez-Villagra et al. (1995) showed that the two differ in carapace shape (sub-rectangular in Amazon animals; oval in Orinoco ones), plastron colour (dark in Amazon animals; light in the Orinoco population), and neck pigmentation (Amazon matamatas have two prominent black bands running along the underside of the neck, separated by a light brown or reddish area. No such patterning is present in the Orinoco population). The two also differ in their growth style, with the carapace becoming larger (in relation to the plastron) faster in Orinoco matamatas than Amazon ones (Sánchez-Villagra et al. 1995) [adjacent images from Sánchez-Villagra et al. (1995)].
These differences are consistent across ontogeny and seem to indicate that two readily distinguishable forms are present. If you want to, you could regard them as separate species – as suggested by Sánchez-Villagra & Scheyer (2010) – or subspecies. A number of specimens (from an unknown location) show a mosaic of Amazon-style and Orinoco-style features. Maybe the two forms are morphs that grade into one another. Alternatively, perhaps the ‘mosaic’ individuals come from a hybrid zone existing between two recently diverged relatives. But that hypothetical hybrid zone could also be between two highly distinct relatives that diverged a long time ago – we just don’t know. Yet. Sánchez-Villagra et al. (1995) noted that their study was preliminary and that more data was needed. They also said that the distinct Amazon and Orinoco forms would be named in time. So far as I can tell, the variation present within living matamatas has yet to be studied further and the two forms haven’t been named. Do say if you know otherwise.
The extinct ones
Having mentioned the possibility of different matamata species, did I mention the extinct ones? No, I deliberately saved this bit until last. Two definite fossil matamatas are known: C. lewisi from the Miocene Urumaco Formation of Venezuela, and C. colombiana, first named from the Middle Miocene Villavieja Formation of Colombia but later reported from the Upper Miocene of Estado do Acre, Brazil and the Lower Miocene Barzalosa Formation of Colombia. Both species were named by Roger C. Wood in 1976, though the C. colombiana holotype had actually been discovered as early as the mid-1940s (Wood 1976) [that holotype is shown here; from Wood (1976)]. The Lower Miocene records make C. colombiana the oldest verified matamata (though read on). Note that the Brazilian records of C. colombiana were reidentified as C. lewisi by Cadena et al. (2008).
‘Small’ fossil matamatas from various Brazilian localities (as in, similar in size to living matamatas) have been intimated to represent an additional species, but the possibility that they are young specimens of C. lewisi and/or C. colombiana also exists (Lapparent de Broin et al. 1993). Plio-Pleistocene matamata fossils from Brazil were said by Wood (1976) to perhaps represent a new species, though this hasn’t been followed up so far as I can tell.
Anyway, so, the oldest matamatas are from early on in the Miocene (somewhere around 20 million years ago). However, Broin & de la Fuente (1993) identified a single cervical vertebra from the Upper Cretaceous of Argentina as that of a possible stem-matamata. That’s not impossible – after all, there’s good evidence from fossils that the chelid radiation was well underway by the latter part of the Cretaceous – but better evidence is definitely needed before we can be sure that the matamata lineage really extends back that far (the phylogenetic position of matamatas relative to other chelids is controversial: see the ‘long, fat neck’ article). Possible close relatives of matamatas (namely Lomalatachelys neuquina from the Santonian Bajo de la Carpa Formation Argentina) have also been identified from the Cretaceous (Lapparent de Broin & de la Fuente 2001).
Both C. colombiana and C. lewisi share with the living matamatas the presence of three carapacial ridges composed of prominent convexities (five along the dorsal midline, and four on both of the side ridges), though the convexities on those ridges are lower and more homogenous in C. lewisi than in the others. C. colombiana has approximately parallel lateral carapace margins while the carapace of C. lewisi flares out posteriorly and the lateral edges flare outwards. Others features that allow the species to be distinguished include details of shell bone shape and the form of the pelvic scars (the raised areas on the shell bones present where the pelvic bones contact the shell). If you need the details see Wood (1976) and Cadena et al. (2008).
Incidentally, C. lewisi makes a guest appearance in one of Jorge González’s excellent illustrations from Sánchez-Villagra et al.’s Urumaco & Venezuelan Paleontology. Part of the picture concerned features on the cover (shown above); you should be able to see the matamata down at bottom left (obscured by the names of the editorial team). If you’re interested in South American Cenozoic vertebrates, Urumaco & Venezuelan Paleontology is a must-have: check it out.
Big – but how big?
What makes these fossil matamatas all the more interesting is that they are somewhat larger than the living ones, perhaps much larger. As we’ve seen in previous articles, modern matamatas are fairly sizeable turtles. Carapace lengths of 40-50 cm have been reliably reported (the record is probably 53 cm). Because the animal’s neck is typically about similar in length to the carapace, a big modern matamata can reach 1 m in total (a matamata this big weighs between 10 and 12 kg). There are rumoured, unconfirmed references to modern matamatas with carapace lengths of over 120 cm (this would mean a total length – with neck outstretched – of around 2 m) but, alas, such accounts are almost certainty exaggerations.
I think exaggerations have also affected the fossil species. The type specimen of C. lewisi has a carapace length (CL) of 45.5 cm and there are specimens with a CL of 50 cm (Wood 1976). This is smaller than the biggest modern matamata. Yet authors have said that C. lewisi is about 10-20% longer in carapace length than the largest C. fimbriata specimen (Wood 1976, Sánchez-Villagra & Scheyer 2010). So far as I can tell, a big C. lewisi would be a large turtle, but not one any bigger than a big modern matamata.
C. colombiana was definitely bigger and both Wood (1976) and Sánchez-Villagra & Scheyer (2010) stated that it could be 50-100% larger than the largest authenticated specimens of C. fimbriata. Yes, as much as twice the size. Assuming this to be correct, it would give a big C. colombiana a CL of about 1 m and hence a total length (again, with outstretched neck) of about 2 m. That’s a very impressive matamata (though note that it’s not bigger than those unconfirmed giant modern specimens). Again, however, I’m not sure that this is precisely correct. The holotype of C. colombiana has a CL of 54.8 cm and the largest reported specimen has an estimated CL of 63 cm (Wood 1976). That’s certainly not 100% bigger than the biggest modern matamata, and it’s not 50% bigger either! Nevertheless, it’s big, and I’m not unhappy with the concept of a matamata that (with neck outstretched) would have reached about 1.2 m in total.
Yet there are claims of much, much larger individuals. Within the last year or two a news items on a Brazilian TV show reported the discovery of a fossil matamata (I assume a specimen of C. colombiana) in which the carapace length alone was 2.46 m. If you don’t believe me, the image above is a screenshot (the relevant segment is online here: not working for me at the moment, alas). Let’s pretend for a moment that this is correct. Assuming that a matamata this big would be isometrically similar to a normal-sized modern matamata, we would have to imagine a neck more than 2 m long, and hence a total length of over (or about) 4 m. A 4 m long matamata. That’s such an awesome idea that I couldn’t help but produce the image you see here. Do take it with a substantial pinch of NaCl.
Of course, that 2.46 m CL is definitely wrong. I think. No matter what it says in that screenshot, there’s no way that the carapace concerned is really that long – it just doesn’t look big enough compared to the other objects that can be observed in the film (like the adjacent table, the floor tiles, the other fossils etc.). So, how did this mistake come about? Perhaps someone said that the whole animal might be 2.46 m long, but even this seems just about unbelievable when the maximum authenticated CL for any matamata is substantially less than 1 m. Or have I missed something?
Whatever the truth, these big, extinct matamatas would undoubtedly have been fascinating creatures, and they were made all the more so by the fact that they lived alongside other giant pleurodires (like Stupendemys), an assortment of giant crocodilians (Purussaurus, Mourasuchus, Charactosuchus and so on) and a diversity of sloths, toxodonts, litopterns and large rodents.
Is it with thoughts of giant fossil matamatas fresh in our minds that we bring the Tet Zoo matamata series to a close, at last. I haven’t done much on other chelids, nor on pleurodires as a whole but, hey, there’s still the future. I owe several people kind thanks for their assistance with the matamata series: thanks to Markus Bühler, Mike Habib, Mark Hollowell and Marcelo Sánchez-Villagra. For the previous articles in the series, see…
- Matamata: turtle-y awesome to the extreme
- The familiar Matamata, known to us all since the 1700s, and its long, fat neck (matamatas part II)
- “Adaptation perfected” (possibly) in a turtle’s head (matamatas part III)
- Turtles that suck, turtles that blow (matamatas part IV)
And for previous Tet Zoo articles on turtles see…
- Giraffe-necked giant tortoises
- Giant African softshells – wow
- Gilbert White’s pet tortoise, and what is ‘grey literature’ anyway?
- The goat-eating hot water bottle turtles
- Hard-shelled sea turtles and a diet of glass
- Terrifying sex organs of male turtles
And for more on neat South American Cenozoic tetrapods, see…
- Ten things you didn’t know about sloths
- Stupidly large snakes, the story so far
- Five things you didn’t know about armadillos
- Life-size two-dimensional condors and teratorns
- Dude, where’s my astrapothere?
- Purussaurs: monster caimans of the Miocene
- Snorki the giant’s friends and relatives
- What was that skull? (glyptodonts)
- 2007: a good year for terror birds and mega-ducks
- Long-snouted marsupial martens and false thylacines
- Marsupial ‘bears’ and marsupial sabre-tooths
Wow, that’s actually quite a lot. Much more to come.
Refs – –
Broin, F. de & de la Fuente, M. S. 1993. Les tortues fossils d’Argentine: synthèse. Annales de Paléontologie 79, 169-232.
Cadena, E., Jaramillo, C. & Paramo, M. E. 2008. New material of Chelus colombiana (Testudines; Pleurodira) from the Lower Miocene of Colombia. Journal of Vertebrate Paleontology 28, 1206-1212.
Lapparent de Broin, F. de, Bocquentin, J. & Negri, F. R. 1993. Gigantic turtles (Pleurodira, Podocnemididae) from the Late Miocene-Early Pliocene of south western Amazon. Bulletin de l’Institut Francais d’Études Andines 22, 657-670.
– & de la Fuente, M. S. 2001. Oldest world Chelidae (Chelonii, Pleurodira), from the Cretaceous of Patagonia. Comptes Rendus de l’Academie des Sciences de Paris 333, 463-470.
Sánchez-Villagra, M. R., Pritchard, P. C., Paolillo, A. & Linares, O. J. 1995. Geographic variation in the matamata turtle, Chelus fimbriatus, with observations on its shell morphology and morphometry. Chelonian Conservation and Biology 1, 293-300.
– . & Scheyer, T. M. 2010. Fossil turtles from the northern neotropics: the Urumaco sequence fauna and finds from other localities in Venezuela and Colombia. In Sánchez-Villagra, M. R., Aguilera, O. A. & Carlini, A. A. (eds) Urumaco & Venezuelan Paleontology. Indiana University Press, Indianapolis, pp. 173-191.
Wood, R. C. (1976). Two new species of Chelus (Testudines: Pleurodira) from the Late Tertiary of northern South America. Breviora, 435, 1-26