CLIMBING CROCS

[darren.naish@port.ac.uk]

Greg Paul asked...

> Do juvenile crocodilians sometimes or often climb, 
> in the manner of young monitors? Again, reference is needed. 

While certain fossil crocs may perhaps have been specialised climbers 
(Paul, has it been published yet?*), extant crocs can and 
apparently **very occasionally** do climb. I've been aware of this 
for years as I recall a segment on a TV documentary where a baby Nile 
croc was climbing around in a tree about 5 ft off the ground. 

Also, believe it or not, there were feral baby crocodiles running 
around in England in the last century and the fact that they used to 
hide up trees was often mentioned. Though I am certain I have read 
this, and therefore have the reference somewhere in my library, I 
can't find it: Michell and Rickard (1981), a book that deals with 
lots of obscure and anecdotal zoological stuff and has a fair-sized 
segment on the English crocodiles (during the last century, these 
animals were referred to as 'debased saurians' and, some time in the 
1850s, it was even suggested that they represented living, degenerate 
descendants of dinosaurs) does not mention the tree-climbing bit. 
There is no doubt that these animals were crocodiles, BTW, as some 
specimens were preserved, stuffed and institutionalised. Woodcuts 
were made of others.

Moving toward rather less dodgy ground, there have been occasional 
references in the technical literature to occasional arboreality in 
crocs. In one of his papers (either 1972, 1974 or 1977: haven't 
had time to check) Alick Walker cited arboreality in primitive 
crocodylomorphs as a character shared with birds, and noted 
that extant crocodile juveniles apparently preserve this primitive 
behaviour. Reviewing Walker's phylogenetic proposals, Tarsitano and 
Hecht (1980) listed Walker's crocodile-bird characters, and, as 
character (14), wrote..

'(14) Crocodilians were originally arboreal as evidenced by the 
climbing ability of juvenile crocodilians, the morphology of the 
tarsus, long humerus, pneumatization of the skull and limbs of 
fossils crocodilomorphs, marked inward and forward curvature of the 
lower half of the tibia and reduction of the first metatarsal.'

TARSITANO, S. and HECHT, M.K. 1980. A reconsideration of the 
reptilian relationships of _Archaeopteryx_. _Zool. J. Linn. Soc._ 69: 
149-182.

Eberhard (Dino) Frey also mentions arboreality in extant crocs in his 
paper..

FREY, E. 1988. Das Tragsystem der Krododile - eine biomechanische und 
phylogenetische Analyse [The carrying system of crocodilians - a 
biomechanical and phylogenetical analysis]. _Stuttgarter Beitrage zur 
Naturkunde Seria A (Biologie)_ 426: 1-60.

(Note the spelling mistake in the title). This paper is (obviously) 
all in German, and I only know about the arboreality section because 
on the way back from a trip to Germany some student hitchhikers we 
were travelling with pointed it out to me. Tree-climbing in crocs is 
mentioned on p. 9. I will not quote the section as (a) I am unsure as 
to which section specifically talks about arboreality and (b) it is 
in German. Dino (pers. comm.) also told me that arboreality in small 
crocodiles is entirely plausible. 

The fact that small crocodiles, as well as things like bears and 
goats, are able climbers indicates that such dinosaurs as small 
theropods and ornithopods were surely capable of arboreality too. 
Though this is a fashionable idea now, it is certainly not new and 
was noted as early as 1866 (Naish, in prep.). Is anyone aware of any 
climbing dinosaur references that predate 1866?

* No mention of it in the paper that names _Mekosuchus 
whitehunterensis_.

DARREN NAISH
darren.naish@port.ac.uk