Posted by: Rob Viens | November 22, 2012

The Tale of Bufo and Lacera Part I

On the 20th Darwin was back out “naturalizing” on the Mount (see Ascending the “Mount”). Both his diary and Zoological Notebook imply that today was all about herpetology:

“Went out collecting on the Mount.— In the course of my walk I came quite close to two of the great lizards of this country.— From the nose to end of tail the length must have been at least 3 feet.” (Nov 20)

In searching for information about the lizards of Uruguay I came across some interesting things. The first thing I found was a complete list of the reptiles of Uruguay (about 65 of the them).  This list comes from a study on the status of reptiles and amphibians in Uruguay (check it out via the link). In general, the most critically endangered reptile species in Uruguay are turtles and snakes – most lizards seem to be holding their own for the moment. For the sake of completeness, here is the list of reptiles of Uruguay from the report linked above:

lizards of Uruguay

Darwin refers to the lizards he saw as “Lacerta”. In general this means “lizard”. More specifically it refers to a genus of lizard that Darwin would have been familiar with from home (as it seems to be an Old World genus). Incidentally, Lacerta lives on in the sky as the name of  a constellation in the Northern Hemisphere – Lacerta the Lizard, aka the line of stars that, with a vivid imagination, look like a lizard…

Lacerta the Lizard (from unknown historic source)

constellation lacerta

In the end, it is not clear which type of lizard Darwin was talking about.  The only descriptive note we have is that it was large. Size would appear to rule out the most diverse group of lizards in Uruguay – the worm lizards. These interesting little carnivorous lizards look more like a large earthworm (really – it is very odd). Their shape is an adaptation to their burrowing lifestyle – they spend much of their life underground where they hunt for their prey. As legs can be a real hinderance in a burrow (and can sometimes get you hung up and result in your death), natural selection as led to a greatly reduced limb size.  Take a look for yourself in this picture of the Baja Worm Lizard (Bipes biporus) (from http://www.amazingworldstuffs.com/):

Baja Worm Lizard

At least one of these worm lizards does deserve mention – Amphisbaena darwinii – Darwin’s Ringed Worm Lizard.  It is one of the many species that now bear Darwin’s name.

Darwin’s Ringed Worm Lizard (from http://naturezabrasileira.com.br/)

Darwin’s Ringed Worm Lizard

Although worm lizards make up a significant fraction of the lizard species in Uruguay, it is more likely that the lizards Darwin encountered today were more traditional (as the Lacerta he is familiar with are more common lizards). The size also implies that it may have been a black and white tegu lizard (Tupinambis merianne) which can grow to 3 to 4 feet in length.

Black and White Tegu (from http://www.scserp.com/)

tegu lizard

These omnivorous lizards are actually sold as pets today. One site even suggests that they like and even seek out human attention (like a pet cat might).

The 21st found the Beagle preparing for travel and Darwin “whining” some more about his dislike for the countryside.  Yes – I said it – Darwin did like to whine on occation…

“All day long provisions & stores are hoisting in; never, without excepting Plymouth, have I seen the ship, even the quarter deck crowded with all sorts of things.— I am glad of it, for I am impatient to be again at sea.— I suspect however before our return there will oftener be occasion for patience than for the contrary extreme.” (Nov 21)

Tomorrow – Part 2 – the story of Bufo… (RJV)

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