Apes and monkeys evolution, new research

This 2008 video is called Aegyptopithecus Mandible Fragments.

From the American Museum of Natural History in the USA:

Fossil suggests apes, old world monkeys moved in opposite directions from shared ancestor

Hip joint study could help explain why apes, humans, and Old World monkeys move so differently

In terms of their body plan, Old World monkeys — a group that includes primates like baboons and macaques — are generally considered more similar to ancestral species than apes are. But a new study that analyzes the first well-preserved femur of Aegyptopithecus zeuxis, a common ancestor of Old World monkeys and apes, suggests that as far as locomotion goes, apes and Old World monkeys each evolved a way of moving that was different from the ancestral species as they adapted to different niches in their environments.

“Our study shows that Aegyptopithecus preserves an ancient hip morphology not present in living anthropoid primates,” said Sergio Almécija, a paleoanthropologist and evolutionary biologist in the Division of Anthropology at the American Museum of Natural History who is first author on the study, which was published in Nature Communications this week. “As far as the hip is concerned, it seems that apes, humans, and Old World monkeys have all parted ways long ago — which would explain why they move around so differently today.”

The fossil analyzed in the study was discovered in 2009 and is the most complete femur of Aegyptopithecus, a 15-lb (7-kg) likely tree-dwelling species that lived in Egypt about 30 million years ago, close to the time when hominoids (the group that includes apes and humans) split from the larger group that includes Old World monkeys. A well-preserved femur allowed researchers to glean details about the hip joint, a major anatomical region for inferring locomotion, using a combination of 3D morphometric analysis and evolutionary modeling.

For the analysis, the authors compared the fossil bone to other extinct and modern species, including humans, chimpanzees, and Victoriapithecus and Homunculus (extinct Old World and New World monkeys, respectively). The evolutionary modeling analysis used in the study included a method that was developed to identify convergent evolution in anole lizards in the Caribbean, which have independently developed comparable niche-specific adaptations across various islands.

The results indicate that the ancestral hip joint is, from an evolutionary perspective, as far from the hip joint of modern Old World monkeys as from those of the great apes — suggesting that each group evolved a distinct way of moving as they specialized for success in different environmental niches.

In addition, evolutionary modeling suggests that living great apes — including orangutans, chimpanzees, and gorillas — may have independently developed similar hip joint anatomy that allows wide-ranging, flexible movement through their arboreal habitats.

“What I find really exciting about the modeling approach is that we can develop better hypotheses about what drove the divergence of apes and monkeys, and the emerging picture is that navigating the environment is one of the key factors,” said Ashley Hammond, assistant curator in the Division of Anthropology and an author on the study.

Southern lesser galago video

This 28 October 2019 video from Botswana says about itself:

The Southern Lesser Galago, also known as a Bushbaby, is perfectly adapted to hunt insects at night. Their tiny bodies are offset by their large, saucer-like eyes, and they will wash their feet and hands in their own urine to make them stickier and help in climbing trees.

Madagascar aye-aye lemurs have six fingers

This June 2015 video says about itself:

Brian Cox Meets An Aye-Aye | Wonders of Life | BBC

Professor Brian Cox gets a rare and up-close look at a sedated aye-aye, known for it’s unusual way of hunting for food.

By Sofie Bates in Science News, October 22, 2019 at 4:25 pm:

Aye-ayes just got weirder with the discovery of a tiny, sixth ‘finger’

An extra digit, a pseudothumb, may help the primates grip objects

Aye-ayes just got even more unusual. The tiny lemurs of Madagascar, known for their large cartoonish ears and continuously growing incisor teeth, also have a sixth “finger” on each hand.

The extra digit — a nubby little “pseudothumb” made of bone and cartilage — can move in three directions and carries its own distinctive fingerprint, researchers report October 21 in the American Journal of Physical Anthropology.

“It’s more than just a nub. It actually has a lot of function to it,” says study coauthor Adam Hartstone-Rose, a comparative anatomist at North Carolina State University in Raleigh. The pseudothumb, which is manipulated by three muscles, may help aye-ayes (Daubentonia madagascariensis) grip objects or branches.

It’s the first time that a pseudothumb has been discovered on any primate, although some people are born with extra fingers (SN: 6/12/19). Other species also have pseudothumbs, including giant pandas, which use their sixth digits to grasp bamboo stalks (SN: 1/31/19). Giant pandas may have acquired that extra digit after the rest of their fingers became less specialized so that the bears could better walk. That’s not the case with aye-ayes, though, the scientists think.

Instead, the little lemurs’ hands may have become too specialized, with thin, elongated fingers, including an especially long third digit that has a ball-and-socket joint. That finger, in particular, is used in a hunting technique called tap foraging, where the animals tap the finger on dead and rotting wood and use echolocation to find bugs hiding inside. Then the primates bite the wood, puncturing a hole, and again use their long third finger for fishing out bugs and grubs found inside.

“Their fingers became so long and spindly that they were no longer good at finger stuff, like grasping,” Hartstone-Rose suggests. The pseudothumb may compensate for the aye-ayes’ other, overspecialized fingers, he and colleagues say.

This interpretation is plausible, says John Hutchinson, an evolutionary biologist at the Royal Veterinary College at the University of London, who was not involved in the work. But he notes that, in general, scientists “don’t know much about what false digits do in most species.”

Extinct giant lemurs of Madagascar

This 25 September 2019 video says about itself:

Just a few thousand years ago, the island of Madagascar was inhabited by giant lemurs. How did such a diverse group of primates evolve in the first place, and how did they help shape the unique environments of Madagascar? And how did they get winnowed down, leaving only their smaller relatives behind?

Australopithecus anamensis discovery in Ethiopia

This 28 August 2019 video says about itself:

MRD cranium – the face of Australopithecus anamensis

In the Woranso-Mille area, Afar, Ethiopia, a 3.8-million-year-old hominin fossil cranium was discovered. Researchers lead by Dr. Yohannes Haile-Selassie (Cleveland Museum of Natural History/Case Western Reserve University) conclude that the fossil cranium MRD-VP-1/1 belongs to the species Australopithecus anamensis.

From the Max Planck Institute for Evolutionary Anthropology in Germany:

A face for Lucy’s ancestor

August 28, 2019

Summary: Researchers have discovered a remarkably complete 3.8-million-year-old cranium of Australopithecus anamensis at Woranso-Mille in Ethiopia. The 3.8 million-year-old fossil cranium represents a time interval between 4.1 and 3.6 million years ago.

Australopithecus anamensis is the earliest-known species of Australopithecus and widely accepted as the progenitor of ‘Lucy‘s’ species, Australopithecus afarensis. Until now, A. anamensis was known mainly from jaws and teeth. Yohannes Haile-Selassie of the Cleveland Museum of Natural History, Stephanie Melillo of the Max Planck Institute for Evolutionary Anthropology and their colleagues have discovered the first cranium of A. anamensis at the paleontological site of Woranso-Mille, in the Afar Region of Ethiopia.

The 3.8 million-year-old fossil cranium represents a time interval between 4.1 and 3.6 million years ago, when A. anamensis gave rise to A. afarensis. Researchers used morphological features of the cranium to identify which species the fossil represents. “Features of the upper jaw and canine tooth were fundamental in determining that MRD was attributable to A. anamensis”, said Melillo. “It is good to finally be able to put a face to the name.” The MRD cranium, together with other fossils previously known from the Afar, show that A. anamensis and A. afarensis co-existed for approximately 100,000 years. This temporal overlap challenges the widely-accepted idea of a linear transition between these two early human ancestors. Haile-Selassie said: “This is a game-changer in our understanding of human evolution during the Pliocene.”

Working for the past 15 years at the site, the team discovered the cranium (MRD-VP-1/1, here referred to as “MRD”) in February 2016. In the years following their discovery, paleoanthropologists of the project conducted extensive analyses of MRD, while project geologists worked on determining the age and context of the specimen. The results of the team’s findings are published online in two papers in the international scientific journal Nature.

Discovery of the cranium

The Woranso-Mille project has been conducting field research in the central Afar region of Ethiopia since 2004. The project has collected more than 12,600 fossil specimens representing about 85 mammalian species. The fossil collection includes about 230 fossil hominin specimens dating to between more than 3.8 and about 3.0 million years ago. The first piece of MRD, the upper jaw, was found by Ali Bereino (a local Afar worker) on February 10, 2016 at a locality known as Miro Dora, Mille district of the Afar Regional State. The specimen was exposed on the surface and further investigation of the area resulted in the recovery of the rest of the cranium. “I couldn’t believe my eyes when I spotted the rest of the cranium. It was a eureka moment and a dream come true,” said Haile-Selassie.

Geology and age determination

In a companion paper published in the same issue of Nature, Beverly Saylor of Case Western Reserve University and her colleagues determined the age of the fossil as 3.8 million years by dating minerals in layers of volcanic rocks nearby. They mapped the dated levels to the fossil site using field observations and the chemistry and magnetic properties of rock layers. Saylor and her colleagues combined the field observations with analysis of microscopic biological remains to reconstruct the landscape, vegetation and hydrology where MRD died.

MRD was found in the sandy deposits of a delta where a river entered a lake. The river likely originated in the highlands of the Ethiopian plateau while the lake developed at lower elevations where rift activity caused the Earth surface to stretch and thin, creating the lowlands of the Afar region. Fossil pollen grains and chemical remains of fossil plant and algae that are preserved in the lake and delta sediments provide clues about the ancient environmental conditions. Specifically they indicate that the watershed of the lake was mostly dry but that there were also forested areas on the shores of the delta or along the side the river that fed the delta and lake system. “MRD lived near a large lake in a region that was dry. We’re eager to conduct more work in these deposits to understand the environment of the MRD specimen, the relationship to climate change and how it affected human evolution, if at all,” said Naomi Levin, a co-author on the study from University of Michigan.

A new face in the crowd

Australopithecus anamensis is the oldest known member of the genus Australopithecus. Due to the cranium’s rare near-complete state, the researchers identified never-before-seen facial features in the species. “MRD has a mix of primitive and derived facial and cranial features that I didn’t expect to see on a single individual,” Haile-Selassie said. Some characteristics were shared with later species, while others had more in common with those of even older and more primitive early human ancestor groups such as Ardipithecus and Sahelanthropus. “Until now, we had a big gap between the earliest-known human ancestors, which are about 6 million years old, and species like ‘Lucy’, which are two to three million years old. One of the most exciting aspects of this discovery is how it bridges the morphological space between these two groups,” said Melillo.

Branching out

Among the most important findings was the team’s conclusion that A. anamensis and its descendant species, the well-known A. afarensis, coexisted for a period of at least 100,000 years. This finding contradicts the long-held notion of an anagenetic relationship between these two taxa, instead supporting a branching pattern of evolution. Melillo explains: “We used to think that A. anamensis gradually turned into A. afarensis over time. We still think that these two species had an ancestor-descendent relationship, but this new discovery suggests that the two species were actually living together in the Afar for quite some time. It changes our understanding of the evolutionary process and brings up new questions — were these animals competing for food or space?”

This conclusion is based on the assignment of the 3.8-million-year-old MRD to A. anamensis and the 3.9-million-year-old hominin cranial fragment commonly known as the Belohdelie frontal, to A. afarensis. The Belohdelie frontal was discovered in the Middle Awash of Ethiopia by a team of paleontologists in 1981, but its taxonomic status has been questioned in the intervening years.

The new MRD cranium enabled the researchers to characterize frontal morphology in A. anamensis for the first time and to recognize that these features differed from the morphology common to the Belohdelie frontal and to other cranial specimens already known for Lucy’s species. As a result, the new study confirms that the Belohdelie frontal belonged to an individual of Lucy’s species. This identification extends the earliest record of A. afarensis back to 3.9 million years ago, while the discovery of MRD nudges the last appearance date of A. anamensis forward to 3.8 million years — indicating the overlap period of at least 100,000 years.

Paranthropus prehistoric hominins, video

This 24 August 2019 video says about itself:

Paranthropus Evolution

2 million years ago an upright walking group of hominins roamed Africa. Not our ancestors but Paranthropus. Who were they? How are we related? Did they give us herpes? Also, other questions!

Fossils suggest tree-dwelling apes walked upright long before hominids did. The 11.6-million-year-old bones still don’t tell us how members of the genus Homo became bipeds: here.