A
captive pacarana (public domain)
There are over
2,200 species of modern-day rodent currently known to science, but only a
handful are so radically different from all others that they have been assigned
an entire taxonomic family all to themselves. However, the extraordinary – and
exceptionally large - rodent documented here (and which also happens to be one
of my favourite mammals) has indeed received that rare accolade. Moreover, as
will now be revealed, the history of its scientific discovery - and rediscovery
- is just as remarkable as it is.
The year 1904 was a momentous year for mice, for it marked the rediscovery
of a truly astonishing and extremely mysterious, controversial rodent that
science had dubbed 'the terrible mouse', due to the fact that it was as large
as a fox terrier!
Needless to say, any mouse the size of a small dog is no
ordinary mouse, and in truth this species is not a bona fide mouse at all. If
anything, it more closely resembles a long-tailed, spineless porcupine in
general shape, and sports a handsome grey-black pelage decorated with
longitudinal rows of white spots, which compares well with that of the South
American common paca or spotted cavy Cuniculus paca, which is a fairly
large relative of the guinea pig (but not the world's third largest
rodent, as certain websites erroneously claim).
Common pacas (© HumedoTepezc/Wikipedia)
Indeed, in its native Andean homeland, the 'terrible mouse' is
known locally as the pacarana ('false paca'). Yet it is neither paca nor
porcupine either. Instead, as noted above, it is sufficiently removed from all
living rodents to require its very own taxonomic family, Dinomyidae, thereby
making it one of the most important mammalian discoveries of the past 150 years
- not to mention one of the most elusive. Several prehistoric relatives of the
pacarana have subsequently been described from fossil remains, and some of
these were quite enormous in size (one, Josephoartigasia monesi, which
lived 4-2 million years ago during the Pliocene and early Pleistocene epochs,
was the size of a bison and is the largest rodent presently known to have
existed). However, no other living dinomyids have been discovered, thus making
the pacarana the very last representative of its entire lineage.
Josephoartigasia monesi reconstruction
inspired by the pacarana (© Nobu Tamura/Wikipedia)
Measuring up to 100 cm long and
weighing as much as 15 kg, the pacarana
is the world's third largest living rodent (exceeded only by the capybaras and
beavers – but not by the paca, see above), and was discovered in 1873 by
Prof. Constantin Jelski, curator of Poland's Cracow Museum. Financed by Polish
nobleman Count Constantin Branicki, Jelski was engaged in zoological
explorations in Peru when, one
morning at daybreak, he observed an extremely large but wholly unfamiliar
rodent. It had very long whiskers and a fairly lengthy tail, and was wandering
through an orchard in the garden of Amablo Mari's hacienda near
Vitoc, in the eastern Peruvian Andes. He swiftly dispatched the poor creature,
and sent its skin and most of its skeleton back to Warsaw, where it
gained the attention of Prof. Wilhelm Peters, Berlin Zoo's director, who
meticulously studied its anatomy. Recognising that this huge rodent represented
a dramatically new species, by the end of 1873 he had published a scientific
description of it, in which he named it Dinomys branickii - 'Branicki's
terrible mouse'. The pacarana had made its scientific debut.
19th-Century engraving of the pacarana
specimen encountered by Jelski
Peters's studies disclosed that its anatomy was a bewildering
amalgamation of features drawn from several quite different rodent families. In
terms of its pelage and limb structure, it compared well with the paca, but
unlike the five-toed (pentadactyl) configuration of the latter's paws the pacarana's
each possessed just four toes. Many of its cranial and skeletal features (not
to mention its long, hairy tail) also set it well apart from the paca,
especially the flattened shape of the front section of its sternum (breast
bone), and the development of its clavicles (collar bones).
19th-Century engraving of the common paca
for comparison purposes with the previous engraving of a pacarana
Certain less conspicuous features of its anatomy were
reminiscent of the capybara, but various others (including the shape of its
molar teeth) corresponded most closely with those of the chinchillas. There
were also some additional characteristics that seemed to ally it with the West Indies’ coypu-like
hutias. Little wonder then that Peters elected to create a completely separate
taxonomic family for it!
The pacarana was clearly a major find - yet no sooner had it been
discovered than it vanished. For three decades nothing more was heard of this
'false paca', and zoologists worldwide feared that it was extinct.
Dr Emil Goeldi (public domain)
Then in May 1904, Dr Emilio Goeldi (1959-1917), director of Brazil's Para (now Belem) Museum,
received a cage containing two living pacaranas (an adult female and a subadult
male). These precious animals had been sent from the upper Rio Purus, Brazil,
and proved to be extremely docile, inoffensive creatures, totally belying their
'terrible mouse' image. They were swiftly transferred to Brazil's Zoological
Gardens, but tragically the adult female died shortly afterwards, following the
birth of the first of two offspring that she was carrying.
Rare, early 20th Century photograph of
a captive pacarana
In 1919, a more unusual-than-normal
pacarana was described by Alipio de Miranda Ribeiro. Instead of being
greyish-black in colour, it was brown, so Ribeiro designated it as the type
specimen of a new species, christened D. pacarana. Three years earlier,
the first pacarana recorded from Colombia had been
collected (near La Candela, Huila); in 1921, this became the type of a third
species, D. gigas. During the early 1920s, a series of pacaranas was
procured by Edmund Heller from localities in Peru and also Brazil, so that by the
1930s a number of museum specimens existed, which were then examined carefully
by Dr Colin Sanborn in the most detailed pacarana study undertaken at that
time. Publishing his findings in 1931, he revealed that D. pacarana and D.
gigas were nothing more than varieties of D. branickii, which meant
that only a single species existed after all.
Brown-furred (or faded black-furred?) taxiderm pacarana
specimen at the Berlin Natural History Museum (©
Markus Bühler)
A rarely-glimpsed, nocturnal inhabitant of mountain forests, the
pacarana feeds on leaves, fruit, and grass, usually associates in groups of
four and five, and is hunted as a source of food by its Indian neighbours, but
little else is known about its lifestyle in the wild state. It is currently
classed as a vulnerable species by the IUCN, yet as a result of its secretive
habits and relatively inconspicuous habitat it may be more abundant than
hitherto suspected (nowadays it is known to be fairly common, for instance, in Bolivia’s Cotapata National Park).
Taxiderm
pacarana at Tring Natural History Museum, Hertfordshire, England (©
Dr Karl Shuker)
Due to this
species’ notoriously elusive nature, however, down through the years zoos have prized pacaranas almost as much as giant
pandas - which is why early 1947 was a singularly memorable time for
Philadelphia Zoo. It was then that it received an innocuous-looking crate from legendary
animal dealer Warren Buck of Camden, New Jersey, with the laconic remark: “Here’s a new one on me.
Maybe you know what it is”. When the crate was opened, to everyone astonishment
it contained a living pacarana! And just like Goeldi’s twosome, it proved to be
delightfully tame and affectionate, showing no inclination to bite, and liking
nothing better than to greet its visitors with a cheerful grunt and to sit
upright on its hindlegs crunching a potato or carrot gripped firmly between its
forepaws.
Of the handful of captive pacaranas obtained more
recently and exhibited at such zoos as Zurich (the first to breed them), Basle,
and San Diego (where I was fortunate enough to see my first live pacaranas in
2004), most have been of similarly pacific temperament. Indeed, they actively
seek out their human visitors to nuzzle them and rub themselves against their
legs almost like cats, or even to be picked up and carried just like playful
puppies - truly a species with no desire whatsoever to live up to its
formidable Dinomys designation!
Pacarana depicted on a postage stamp
issued by Equatorial Guinea
Finally: Demonstrating that not only the pacarana but
also the true pacas may well have some extra-large surprises in store for
science is an exciting recent discovery made in Brazil by Dutch zoologist Dr Marc van Roosmalen. There are three
currently-recognised species of true paca. Namely: the above-mentioned common
paca C. paca; the smaller, longer-furred, and less-familiar mountain
paca C. taczanowskii; and Hernandez's mountain paca C. hernandezi,
described and named as recently as 2010 after mitochondrial DNA analyses
confirmed its separate taxonomic status from the mountain paca. These are almost-tailless
rodents normally no more than 60 cm long (often
less), averaging 7 kg in weight, and
adorned with usually four longitudinal rows of white spots on each side of
their blackish-brown-furred body
Mountain paca (© WebmasterRioblanco/Wikipedia)
However, just a
few years ago, Marc encountered – and collected – in Brazil a much larger
form of true paca, known locally as the paca concha. It appears to have
a very wide distribution range, and is distinguished from the two recognised
species by its greater size (weighing up to 13
kg), its lighter fur colour, and the merging of most of its spots
into longitudinal lines.
The
holotype of the currently-undescribed giant paca (© Dr Marc van Roosmalen)
In a scientific paper
currently awaiting publication, Marc has named this extra-large form as a new
species. Several suspected specimens of giant paca are held at Brazil’s Museu
Paraense Emilio Goeldi, where Marc’s holotype of this potential new species,
killed for food by a local hunter on 28
May 2006 near Tucunaré, has been deposited. So perhaps Count Branicki’s
false paca now has a rival among the real pacas in terms both of physical stature
and of complete surprise to the zoological community, thanks to its unexpected
discovery.
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