Macrauchenia spp.

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Macrauchenia spp.


© @ Gabriel Ugueto->

Temporal range: Miocene-terminal Pleistocene (Messinian-Tarantian; 7-0.017Ma)

Scientific classification:

Life
Clade: Neomura
Domain: Eukarya
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Olfactores
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Clade/Order: Therapsida
Clade: Neotherapsida
Clade: Theriodontia
Clade: Eutheriodontia
Clade/Suborder: Cynodontia
Clade: Epicyonodontia
Infraorder: Eucynodontia
Clade: Probainognathia
Superfamily: Chiniquodontoidea
Clade: Prozostrodontia
Clade: Mammaliformes
Class: Mammalia
Clade: Holotheria
Superlegion: Trechnotheria
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria[1]
Clade: Ungulata[1]
(unranked): †Meridiungulata
Order: †Litopterna
Family: †Macraucheniidae
Genus: †Macrauchenia
Species: †M. patachonica
†M. ullomensis
†M. boliviensis

Macrauchenia ("long llama") is a genus of litoptern that lived in South America.

Description:
Macrauchenia was a massive creature, weighing ~1,042.8 kilograms.[2] It walked on three toes, had a bulky body, a long neck, and a comparatively small head. M. patachonica fed on C3 leaves and C4 grasses based on a carbon isotope analysis on its tooth enamel, its brachydonty, its body size, and how wide its rostrum was proportionally.[3] In the forelimbs, the forearm was significantly longer than the humerus while the femur was somewhat longer than the tibia in the hindlimbs. The animal is commonly believed to have possessed a proboscis (arguably the aspect it's most well-known for) in life because of the dorsally-located nares, but its skull supposedly lacks any sign of the facial musculature required for such a structure.* As a meridiungulate, its closest living relatives would be the perissodactyls (rhinos, horses, and tapirs), as was recently found out. They were a sister clade to the perissodactyls, hence they were true ungulates.[1]

Predators and defense against thereof:
Before the Great American Interchange, Macrauchenia would have been preyed upon by sparassodonts and phorusrhacids. Subsequently its predators would have consisted of placental carnivorans.

Supposedly, Macrauchenia would have been capable of turning quickly when running at high speeds.[citation needed] Likewise, it's been proposed it could deliver a powerful kick with the hindlimbs.[4]

Natural history:
Macrauchenia first appeared ~7 million years ago and might have evolved from either Theosodon or Promacrauchenia.

When the Great American Interchange occurred, it was one of the few meridiungulates (and thus litopterns) that survived.[5] It was one of if not the last of its kind. Macrauchenia went extinct at the end of the Pleistocene as a result of whatever caused the end-Pleistocene extinctions.


Skeleton of M. patachonica.

References:

[1] "Ancient proteins resolve the evolutionary history of Darwin's South American ungulates" (Welker et al., 2015).
[2] sedici.unlp.edu.ar/handle/10915/16838?show=full
[3] "Ancient Feeding Ecology and Niche Differentiation of Pleistocene Mammalian Herbivores from Tarija, Bolivia: Morphological and Isotopic Evidence" (MacFadden & Shockey, 1997).
[4] David Lambert, Darren Naish, & Elizabeth Wyse. Dinosaur Encyclopedia: From Dinosaurs to the Dawn of Man (2001).
[5] "The Broken Zig-Zag: Late Cenozoic Large Mammal and Tortoise Extinction in South America" (Cione et al., 2003).

*Will explain in a subsequent post.

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Not that I'd cite Cryptomundo as a reliable source at all (no offense to them) but the following link thereof provides Darren Naish's insight on the plausibility of a trunk in Macrauchenia.

"I had to think hard about Macrauchenia when supervising reconstructions for a kid’s book a while ago, and I can’t say that I am impressed with the evidence for a trunk: so far as I can recall, it actually lacks the muscle attachment sites present in living mammals that have trunks. I…have a long article on them in preparation….I have yet to make up my mind."
cryptomundo.com/cryptozoo-news/no-trunks/

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After proverbially foraging throughout the Internet about elephant bone strength and all that jazz, I actually stumbled upon something very interesting about the idea that Macrauchenia was an agile runner that could have out-turned predators during a high speed chase.

Turns out...it's true!

Swerving as the escape strategy of Macrauchenia patachonica Owen (Mammalia; Litopterna)

Abstract
The Lujanian megamammals (late Pleistocene of South America) show many palaeoautecological peculiarities. The present paper studies one of them, the locomotor habits of Macrauchenia patachonica Owen, through those morphological features related with its possible antipredation strategy. To avoid predation (especially by the sabre-tooth Smilodon Lund), this large litoptern seems to have been particularly adapted to swerving behaviour. This is suggested by the fact that its limb bones have indicators of higher transverse than anteroposterior strength (significantly so in the case of the femur), a feature which is also observed in modern swervers, and not so clearly in other fast running herbivores that do not use swerving so much.

You can read the full paper here.

www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0002-70142005000400007

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I don't think Macrauchenia had the trunk it's often depicted with.

The bizarre South American litoptern Macrauchenia is a showcase animal when one thinks of Pleistocene South America, along with Smilodon, and many other weirdos. But, one thing it’s always been depicted with is a trunk. Most famously, the Walking with Beasts Macrauchenia sports one of these long shnozzes. The reasoning behind this trait is a highly reduced set of nasal bones and nares facing upwards. However, this isn’t quite how trunks work. Trunks need reduced nare bones, but not to the point where they are near nonexistent. The levator nasolabialis and levator labii superioris muscles need a base to work off of when lifting and lowering the trunk. On top of that, the animal would need wide cheek or zygomatic bones, for the levator anguli oris and zygomaticus major muscles, the muscles which help you and I smile, and turn our mouths. Macrauchenia lacks these two basic needs for a trunk. Instead, it has a long, thin face, lacking large zygomatic faces and practically has a blowhole. And another important ingredient, is the lack of the dividing wall of bone in the nares that a large number of mammals have. A far more probable alternative would be for the animal to have a giant resonating chamber in its nostrils, similar to hadrosaurs and a few mammals, past and present.

References:

Dr. Matthew Colbert, 2002, "Tapirus terrestris" (On-line), Digital Morphology. Accessed November 22, 2017 at digimorph.org/specimens/Tapirus_terrestris/.
Chisholm, Hugh, ed. (1911). "Macrauchenia". Encyclopædia Britannica. 17 (11th ed.). Cambridge University Press.

celestialtroodon.blogspot.com/2017/11/is-that-remote-or-are-you-trunked-to.html

Here is a reconstruction of the facial muscles of Macrauchenia by the author of the above blog post.

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Mar 11, 2019 3:28:26 GMT 5 Infinity Blade said:

I don't think Macrauchenia had the trunk it's often depicted with.

The bizarre South American litoptern Macrauchenia is a showcase animal when one thinks of Pleistocene South America, along with Smilodon, and many other weirdos. But, one thing it’s always been depicted with is a trunk. Most famously, the Walking with Beasts Macrauchenia sports one of these long shnozzes. The reasoning behind this trait is a highly reduced set of nasal bones and nares facing upwards. However, this isn’t quite how trunks work. Trunks need reduced nare bones, but not to the point where they are near nonexistent. The levator nasolabialis and levator labii superioris muscles need a base to work off of when lifting and lowering the trunk. On top of that, the animal would need wide cheek or zygomatic bones, for the levator anguli oris and zygomaticus major muscles, the muscles which help you and I smile, and turn our mouths. Macrauchenia lacks these two basic needs for a trunk. Instead, it has a long, thin face, lacking large zygomatic faces and practically has a blowhole. And another important ingredient, is the lack of the dividing wall of bone in the nares that a large number of mammals have. A far more probable alternative would be for the animal to have a giant resonating chamber in its nostrils, similar to hadrosaurs and a few mammals, past and present.

References:

Dr. Matthew Colbert, 2002, "Tapirus terrestris" (On-line), Digital Morphology. Accessed November 22, 2017 at digimorph.org/specimens/Tapirus_terrestris/.
Chisholm, Hugh, ed. (1911). "Macrauchenia". Encyclopædia Britannica. 17 (11th ed.). Cambridge University Press.

celestialtroodon.blogspot.com/2017/11/is-that-remote-or-are-you-trunked-to.html

Here is a reconstruction of the facial muscles of Macrauchenia by the author of the above blog post.

Turns out there's a 2018 study that confirms that yes, Macrauchenia (and other family members) cannot be interpreted as having a true short proboscis.

In conclusion, a true short proboscis must have been present in later representatives amynodontids, astrapotherians, pyrotherians, and possibly some merycoidodonts, among other fossil hoofed mammals. Neither macraucheniids nor any extant hoofed mammals, other than tapirs, can be interpreted as presenting a true short proboscis. In fact, these should be interpreted as cases of prorhiscis.

sci-hub.tw/10.1016/j.jcz.2018.08.005

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Macrauchenia patachonica Owen, 1838: Limb bones morphology, locomotory biomechanics, and paleobiological inferences

Highlights

- Wide scapula movements could compensate for the reduced mobility of a short humerus.

- Lowered head derived in freedom for forelimbs movement increasing the step length.

- Limbs biomechanics increased the food encounter rate by improving acceleration.

- Macrauchenia patachonica probably ran with the neck in a horizontal position.

- The nasal retraction could be an adaptation for dust filtering.

Abstract

Macrauchenia patachonica Owen, 1838 was among the last and largest litopterns, an extinct order of South American native ungulates. Macrauchenia patachonica had anatomical peculiarities as extremely retracted nasals, enlarged cervical vertebrae, and limb bones proportions without good living analogs that lead to asking about its paleobiology. To quantitatively assess the strange combination of limb bone features in M. patachonica, we constructed an indicator of differences in anatomical adaptations for efficient running between forelimb and hind limb (IDFH). We also made a multivariate analysis using data on osteological ratios of living mammals and two other litopterns. We discuss several biomechanical and paleobiological implications of the striking differences between hind limb and forelimb design in M. patachonica. Our main suggestion is that M. patachonica, during fast locomotion, probably used a posture with the neck in a horizontal position.

www.sciencedirect.com/science/article/abs/pii/S0016699521000425

[Exalt]

May 8, 2017 4:45:22 GMT 5 Infinity Blade said:

After proverbially foraging throughout the Internet about elephant bone strength and all that jazz, I actually stumbled upon something very interesting about the idea that Macrauchenia was an agile runner that could have out-turned predators during a high speed chase.

Turns out...it's true!

Swerving as the escape strategy of Macrauchenia patachonica Owen (Mammalia; Litopterna)

Abstract
The Lujanian megamammals (late Pleistocene of South America) show many palaeoautecological peculiarities. The present paper studies one of them, the locomotor habits of Macrauchenia patachonica Owen, through those morphological features related with its possible antipredation strategy. To avoid predation (especially by the sabre-tooth Smilodon Lund), this large litoptern seems to have been particularly adapted to swerving behaviour. This is suggested by the fact that its limb bones have indicators of higher transverse than anteroposterior strength (significantly so in the case of the femur), a feature which is also observed in modern swervers, and not so clearly in other fast running herbivores that do not use swerving so much.

You can read the full paper here.

www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0002-70142005000400007

That article doesn't seem to want to load, so perhaps this is redundant, but I've heard claims that Phorusrhacids would have been quick when moving in a straight line, but would have struggled to turn during the process, which would be consistent with this.

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Aug 21, 2023 7:37:46 GMT 5 Exalt said:

May 8, 2017 4:45:22 GMT 5 Infinity Blade said:

After proverbially foraging throughout the Internet about elephant bone strength and all that jazz, I actually stumbled upon something very interesting about the idea that Macrauchenia was an agile runner that could have out-turned predators during a high speed chase.

Turns out...it's true!

Swerving as the escape strategy of Macrauchenia patachonica Owen (Mammalia; Litopterna)

Abstract
The Lujanian megamammals (late Pleistocene of South America) show many palaeoautecological peculiarities. The present paper studies one of them, the locomotor habits of Macrauchenia patachonica Owen, through those morphological features related with its possible antipredation strategy. To avoid predation (especially by the sabre-tooth Smilodon Lund), this large litoptern seems to have been particularly adapted to swerving behaviour. This is suggested by the fact that its limb bones have indicators of higher transverse than anteroposterior strength (significantly so in the case of the femur), a feature which is also observed in modern swervers, and not so clearly in other fast running herbivores that do not use swerving so much.

You can read the full paper here.

www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0002-70142005000400007

That article doesn't seem to want to load, so perhaps this is redundant, but I've heard claims that Phorusrhacids would have been quick when moving in a straight line, but would have struggled to turn during the process, which would be consistent with this.

It could be argued that a phorusrhacid would be a bit less maneuverable than something like Macrauchenia, being on two legs instead of four. Although, I think you could also argue for the opposite, since the bird is A) much lighter than Macrauchenia and B) they had enormous leg muscles for their size (as ground birds tend to), which could make up for having less legs to produce torque while turning.

That said, given how long Macrauchenia seems to have existed for, this escape strategy clearly worked against a whole slew of predators. Sparassodonts, phorusrhacids, and various carnivorans (cats, bears, and dogs).

[Exalt]

I went to look it up and wow, approximately seven million years?

And of course, it was on this page the whole time, and I missed it...

[Supercommunist]

An animal does not neccessarily need to be flat out better at turning than a predator to get away from it. Studies have shown that lions and cheetahs are faster than zebras and imapla while also having greater acceleration and % greater deceleration capacity, yet zebras escape from lions more often than not.

pubmed.ncbi.nlm.nih.gov/29364874/

[Exalt]

Thank you for informing me.

Although now a question I asked elsewhere must look foolish.

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More than 100 years of a mistake: on the anatomy of the atlas of the enigmatic Macrauchenia patachonica

Ever since the discovery of the first remains of Macrauchenia patachonica by Charles Darwin in 1834, this taxon has puzzled researchers with its peculiar anatomy. Being the best-known member of the family Macraucheniidae and with fossil records in extensive areas of South America between the Middle to Late Pleistocene/earliest Holocene, M. patachonica has been extensively studied over decades, and recently even included in molecular studies. However, there are some elements of its skeleton that have been inadvertently unstudied. One of these elements is the atlas of M. patachonica that due to a misidentification made 159 years ago by the prominent zoologist Hermann Burmeister, was not examined or illustrated by later researchers even with access to excellent specimens. Here, we describe and illustrate the atlas of M. patachonica for the first time, correcting Burmeister’s mistake. Overall, the anatomy of the atlas of M. patachonica is consistent with the anatomy of older macraucheniids. The atlas described by Burmeister as being M. patachonica probably corresponds to that of a bovid. It is noteworthy that most mounted skeletons of M. patachonica present today in museum exhibitions, display a correct atlas derived from a more complete specimen discovered ca. 1904 by the prominent palaeontologist Santiago Roth.

link.springer.com/article/10.1186/s13358-023-00279-1