Peru
2010
"Prehistorical animals – Thalassocnus"
Issue
Date |
21.09.2010 |
ID |
Michel:
2485, Bl. 70
Stanley Gibbons: UPU:
Category: pR |
Author |
Cristian
Alvarez M. –SERPOST S.A. |
Stamps
in set |
1 |
Value |
S/.10.00 -Thalassocnus
littoralis
: fossil
on stamp and reconstruction in block margin
|
Size
(width x height) |
30mm x 40mm |
Layout |
block
with 1 stamp
|
Products
|
FDCx
1 |
Paper |
|
Perforation |
13 ½. |
Print
Technique |
Offset |
Printed
by |
Thomas Grag and Sons –
Peru. |
Quantity |
10.000
|
Issuing
Authority |
Servicios Postales del Peru SA |
In 2010 the Post Authority of
Peru - Servicios
Postales del Peru SA - continue to show natural
heritage of the country discoverdon their stamps. This year a
block depcted scientific
reconstruction and fossil of prehistoric sloth - Thalassocnus
littoralis
is added to "Prehistoric animals"
(Animales
Prehistoricos - Fosiles) set started in 2004.
When
you think of marine mammals, sloths are probably the last thing you’d
expect to take to the water. But from the late Miocene (7-8 million
years ago) to the late Pliocene (3-1.5 million years ago), several
species of giant ground sloths in the genus Thalassocnus
did indeed evolve to take advantage of the aquatic environment. However
even some modern slots can swim.
Official
stamp
description is below.
"If there is something amazing about
paleontology it is a capacity to show us that the life on the
Earth, such as we know it nowadays, is the result of constant changes.
Even the English
naturalist Charles Darwin sketched his primordial ideas about the
biological evolution inspired by fossilized bones of giant sloths and
gliptodonts,
the ancestors of little tree sloths and armadillos in South America.
The
evolution –developed 150 years ago in Darwin’s “The origin of the
species”- is
the
concept that integrates all the sciences of life, now with the help of
genetics
and molecular biology. Like in Darwin’s time, fossils are the most
inspiring
resource for the evolution.
Millions
of years ago, the
desertic
area of Sacaco, north to Arequipa, was a littoral marine environment.
In its
sands lie hundreds of fossils of whales, dolphins, seals, penguins and
sharks
in excellent state of preservation. In 1967, french paleontologist
Robert Hoffstetter visit the area, and was greatly surprised to find
a terrestrial intruder: a sloth between
aquatic species.
It was inicially assumed that the sloth lived on land, near the littoral.
Hoffstetter thought
that their bodies were dragged into the sea by an andian paleo-river,
where
they were buried and preserved with aquatic species. However, something
was
wrong: the skeletons were always found articulated and complete, as if
buried
in the same place of their death - in the sea. What if it really was
an aquatic
sloth? This possibility, though wild, encouraged paleontologists
Christian de
Muizon and Greg McDonald to observe every bone's detail to look for
revealing
clues. In 1995, Muzion and McDonald announced in Nature Magazine, the
existance
of a 4 million year aquatic sloth in Peru.
Some details of its anatomy,
such as
the shape of the premaxilla,
femur
and caudal vertebrae (the bones that make up the tails of
tailed animals) , are
more
similar to
certain aquatic mammals that to others extinct sloths. Various
scientifics
shown skeptic.

|

|
After
almost 15 years and many
dicoveries made by Mario Urbina, 5 species of the aquatic sloth
Thalassocnus
were described, all of them found in marine deposits nearby Sacaco,
but
into
rocks belonging to succesive epochs from 9 to 2,5 million years ago.
This only
record, let us track the first splashes in its linnage evolution, and
also
observe the way that certain adaptations to the aquatic environment
were
progressevely accentuated through time. Thalassocnus was a sloth the
size of a
large dog, with long tail and powerful claws. It had simple teeth with
no
enamel. Since the most ancient species (Thalassocnus antiquus) to the
most
modern (Thalassocnus yaucensis) several changes were observed,
especially an
increase in the length and width of the muzzle’s previous region,
related to
obtaining aquatic grass as a new source of food. The radius
bone
morphology
shows
substancial differences in the locomotion way. While Thalassocnus
antiquus has
a long radious bone with a reduced supinator crest, typical of
terrestrial
sloth, in
Thalassocnus yaucensis the radius bone
is short and the supinator crest is
highly
developed as observed in seals and sea lions. Today there is no doubt
that
Talassocnus was an aquatic sloth which spent a long time feeding into
the sea;
but what could have impulsed it to leave its quiet life on land to
adventure
amongst waves infested with sharks? Good question. It is known that the
peruvian coast was already desertic in that epoch. Possibly the scarce
vegetation in the coasted desert lead to the search of an alternative
resource
in the beached algae during low tide. After many generations, some of
them
adventured to look for algae and marine grass into the sea. As this
survival
strategy was good enough, those individuals who had small anatomical
advantages
to live and feed in the sea –therefore the more suitable - had more
opportunities to reproduce and fix its genes in their offspring. The
mechanism
of evolution proposed by
Darwin –natural
selection- was on the road.
In
2008, we published, with
chilean
colleague, at the Journal of Vertebrate Paleontology, the first remains
of
Thalassocnus discovered outside of Sacaco, almost 1500 km away, on
rocks of
marine origin in Bahia Inglesa (English Bay), in the north of Chile.
This made
us think that Thalassocnus dominated a vast littoral territory of
homogeneous
ecological characteristics. As we can imagine their bones were found
among
whale and dolphin remains. Recently, new Thalassocnus remains were
discovered in
Ica, 180 km north to Sacaco.
The
evolutive travesy of
aquatical
sloth Thalassocnus finished 2 million years ago. The bays of quiet warm
water
that existed for millions of years, made a way to a lineal coast of an
agitated
sea, just like we know it today. The wide cover of sea grass
dissapeared and
the Thalassocnus’ linnage was extinted. Instead, other terrestrial
sloths
evolved to become the largest mammals that lived in South America."
Rodolfo
Salas Gismondi. Curator. Verbratete
Paleontology
Department. Natural History Museum. UNMSM.
Products
FDC
|
Used covers
|
|
|
Acknowledgement:
Many thanks to fellow stamp collector Romina Aimar from Argentina , for her help in translation of original text from Spanish to English
References:
Serpost Brochure
Nocturnalsea
Laalaps
Last update 21.11.2017
Any feedback, comments or even complaints
are welcome: [email protected] (you
can email me on ENglish, DEutsch, or RUssian)