Macrauchenia
Name:
Macrauchenia
(Long llama).
Phonetic: Mak-row-chen-e-a.
Named By: Richard Owen - 1838.
Classification: Chordata, Mammalia, Litopterna,
Macraucheniidae.
Species: M. patachonica (type),
M.
formosa, M. intermedia, M. ullomensis.
Diet: Herbivore.
Size: 3 meters long.
Known locations: Throughout South America with
remains known from Argentina, Bolivia, Chile and Venezuela.
Time period: Late Tortonian of the Miocene through
to the end of Tarantian of the Pleistocene, possibly into the early
Holocene.
Fossil representation: Multiple specimens.
Every
now and then in palaeontology an animal comes along that just doesn’t
seem like it should have existed at all. Macrauchenia
is one such
individual creature due to a very bizarre mix body features that have
ended up in a mix-match of different creature parts.
To
begin first imagine a four legged creature with similar body
proportions to a camel, but the first thing you do is lose the hump.
The front legs of this creature have short upper portions and long
lower portions which indicate a runner. The back legs however have
much more developed upper portions and proportionately shorter lower
leg areas resulting in back legs that are not suited to fast running at
all. At the ends of these legs are feet that are more like what you
might expect on a rhinoceros, not especially good for running, but
good for traction. A final feature at this point is what could have
either been a small trunk or well developed prehensile lip that grew
from the tip of the snout like a tapir or elephant. Now consider that
as a litoptern Macrauchenia was related to none of
these other animals
and you are on the tip of the proverbial iceberg in trying to
understand this creature.
Fortunately
science has helped answer some of the questions about Macrauchenia
with
carbon isotope analysis of tooth enamel from Macrauchenia
teeth
revealing that it ate both plants and grasses. This helps clear up
the dietary confusion because the prehensile lip/trunk is typically
seen as a feeding adaptation stripping leaves from shrubs and low
growing trees, whereas the high crown teeth are more indicative of
chewing on grasses. The fact that carbon isotopes from both types of
plants have been found reveals that Macrauchenia
was an opportunistic
herbivore that both browsed and grazed, a foraging strategy which
could explain its expansion across South America which has been
revealed by its broad geographic distribution of remains.
The
legs and feet are much harder to explain because of the great
difference in form between rear and fore legs. One idea though is
that rather than relying upon speed for survival, Macrauchenia
might
have opted for greater manoeuvrability. This would have been of
particular benefit if Macrauchenia lived in areas
which had difficult
terrain that was hazardous for fast running animals that were not as
steady on their feet.
Macrauchenia
was one of if not the last of litoptern mammals and may have survived
long enough to see the early Holocene period. In the early stages of
its existence it would have probably been hunted by South America’s
apex predators of the time, the phorusrhacid
terror birds. Some of
the larger members of this group such as Brontornis,
Kelenken
and
Phorusrhacos
itself would have all been capable hunters with the size,
reach, power and speed to be a threat to even fully grown
Macrauchenia. An additional threat, particularly
to smaller
juvenile Macrauchenia was the sabre-toothed
marsupial Thylacosmilus.
Even
with all of these predators however this was still the golden time for
Macrauchenia as this was before the event called the
Great American
interchange. With the creation of the Isthmus of Panama, a
permanent land bridge between North and South America, North American
animals began to spread into the same habitats as Macrauchenia.
Not
only were these new herbivores which provided increased competition for
existing food resources, but new predators such as proper
sabre-toothed cats like Smilodon
populator as well as other predators
like the dire
wolf. Even if Macrauchenia
did rely upon
manoeuvrability for predator escape, Smilodon
likely hunted by ambush
and was supremely well adapted for grappling with large and powerful
prey. Macrauchenia would have had even less
chance dealing with
wolves since they hunt by packs and rely more upon forcing their prey
to exhaust themselves by overexertion before they go in for the kill.
By running around all over trying to evade many predators at once,
Macrauchenia would simply make it even easier for
the wolves.
As
the other litopterns vanished, Macrauchenia held
out until the
arrival of the first people in South America who also crossed over the
Isthmus of Panama towards the end of the Pleistocene. Although early
humans often get the blame for wiping out the Pleistocene megafauna
like Macrauchenia, this previously ‘catch all’
theory is not as
widely accepted as it once was. Climatic shifts during the closing
stages of the Pleistocene are now also thought to have been a
contributing factor to the demise of much of the megafauna and with
Macrauchenia populations already weakened by
increased competition,
Macrauchenia was even more susceptible to the
events of a world
changing around it.
Further reading
- Description of Parts of the Skeleton of Macrauchenia
patachonica. -
In Darwin, C. R. Fossil Mammalia Part 1 No. 1. The zoology of the
voyage of H.M.S. Beagle. London: Smith Elder and Co. - Ricahrd owen -
1838.
- Informe preliminar de los progresos del Museo La Plata, durante el
primer semestre de 1888. - Boletim del Museo de La Plata II:1-35 - F.
P. Moreno - 1888.
- Ancient feeding ecology and niche differentiation of Pleistocene
mammalian herbivores from Tarija, Bolivia: morphological and isotopic
evidence. - Paleobiology (Paleontological Society) 23 (1): 77–100 - B.
J. McFadden & B. J. Shockey - 1997.
- Ancient collagen reveals evolutionary history of the endemic South
American 'ungulates'. - Proceedings of the Royal Society B: Biological
Sciences. 282. - M. Buckley - 2015.
- Ancient proteins resolve the evolutionary history of Darwin's South
American ungulates. - Nature. 522 (7554): 81–84. - F. Welker, M. J.
Collins, J. A. Thomas, M. Wadsley, S. Brace, E. Cappellini, S. T.
Turvey, M. Reguero, J. N. Gelfo, A. Kramarz, J. Burger, J.
Thomas-Oates, D. A. Ashford, P. D. Ashton, K. Rowsell, D. M. Porter, B.
Kessler, R. Fischer, C. Baessmann, S. Kasper, J. V. Olsen, P. Kiley, J.
A. Elliot, C. D. Kelstrup, V. Mullin, M. Hofreiter, E. Willerslev,
J.-J. Hublin, L. Orlando, I. Barnes & R. D. E. MacPhee - 2015.
- A mitogenomic timetree for Darwin's enigmatic South American mammal
Macrauchenia patachonica. - Nature Communications. 8: 15951. - M.
Westbury, S. Baleka, A. Barlow, S. Hartmann, J. L. A. Paijmans, A.
Kramarz, A. M. Forasiepi, M. Bond, J. N. Gelfo, M. A.Reguero, P.
L�pez-Mendoza, M. Taglioretti, F. Scaglia, A. Rinderknecht, W. Jones,
F. Mena, G. Billet, C. de Muizon, J. L. Aguilar, R. D. E. MacPhee
& M. Hofreiter - 2017.
- Fantastic beasts and what they ate: Revealing feeding habits and
ecological niche of late Quaternary Macraucheniidae from South America.
- Quaternary Science Reviews. 231: 106178. - Karoliny de Oliveira,
Tha�sa Ara�jo, Alline Rotti, Dimila Moth�, Florent Rivals &
Leonardo S. Avilla - 2020.
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