Earliest Fossil Hominins Quiz

Thumai had a relatively small brain, measuring approximately 350 cubic centimeters, comparable to chimpanzees.

Unlike apes, Thumai had relatively small canine teeth, though not much smaller than some female chimpanzees.

Human nuchal muscles extend from the shoulders to the back of the skull, helping to keep the head upright and balanced on the spinal cord.

Chimpanzee nuchal muscles attach high on the back of the skull because they walk on all fours, needing strong neck muscles to hold their head up.

The foramen magnum, the hole in the base of the skull where the spinal cord exits, is located in the center of the skull in humans due to our upright posture.

Quadrupeds, like dogs, have their foramen magnum located at the very back of the skull because their head is held forward.

Thumai's foramen magnum is positioned more towards the rear of the skull than in humans, but further forward than in chimpanzees, indicating a possible intermediate posture between quadrupedal and bipedal locomotion.

The location of Thumai's nuchal muscle attachment suggests it stood upright more than apes, supporting the possibility of bipedalism. However, some researchers argue the location of its foramen magnum might not indicate full bipedality.

An early hominin species that lived in Africa around 3.9 to 2.9 million years ago. Animensis fossils display a blend of primitive and advanced features, including a small brain, ape-like cranium and dentition, but also a bipedal skeleton with longer legs and shorter arms compared to earlier hominins.

Animensis possessed features similar to earlier apes, including a small brain size (~370 cubic centimeters), ape-like cranium and dentition, and strong sexual dimorphism in canine size. These features suggest a closer relationship to chimpanzees than modern humans.

Despite its primitive features, Animensis also exhibited several advanced characteristics like a postcranial skeleton adapted for full bipedalism, longer legs, shorter arms, and non-prehensile feet. This suggests a transition towards a more upright, terrestrial lifestyle.

A hominin species that lived in East Africa between 4 and 3 million years ago, known for the famous 'Lucy' fossil. Afarensis had a small brain, ape-like features, but was fully bipedal with longer legs and shorter arms. Its fossils were found in Ethiopia, Tanzania, and Kenya.

Another hominin species that lived in South Africa between 3.3 and 2.1 million years ago. Africanus had a slightly larger brain than afarensis, but still retained many ape-like features. It possessed a mix of arboreal and terrestrial adaptations.

A mode of locomotion where an animal walks on two legs, allowing for upright posture and efficient locomotion on land. Animensis is the earliest known hominin that definitely possessed full bipedalism.

Australopithecines, including Animensis, afarensis, and africanus, lived in diverse environments, ranging from wooded grasslands to forests. They likely combined arboreal (tree-climbing) and terrestrial (ground) behaviors, using trees for shelter and food access.

Australopithecus afarensis, particularly, is considered a likely candidate for being a direct ancestor to the genus Homo. Both afarensis and africanus exhibit features that bridge the gap between earlier hominins and later Homo species.

Australopithecines, like Afarensis and Africanus, had a 'U' shaped dental arcade with parallel tooth rows, similar to apes. This contrasts with modern humans' parabolic shaped dental arcade.

Australopithecines had significantly larger molars compared to modern humans and chimpanzees. This is particularly prominent in Africanus.

Africanus had a more robust and strongly built lower jaw, or mandible, compared to Afarensis.

Australopithecines had more human-like hands, characterized by shorter fingers and a slightly larger thumb, as well as more human-like wrist bones compared to apes.

The femur, or upper leg bone, in Australopithecines like Afarensis and Africanus indicates obligate bipedalism. It has an elongated neck, pushing the ball of the femur away from the shaft, and an increased angle, angling the legs towards the body's center.

Australopithecines had a more modern-looking pelvis, similar to humans, which served as a stable anchor for legs. This contrasts with chimpanzees, whose pelvis is adapted for greater range of motion in legs, essential for climbing.

Australopithecines had a diastema, a gap in the teeth between the canine and incisors. This feature is absent in modern humans.

While obligate bipedalism likely appeared earlier, Australopithecines like Afarensis and Africanus exhibited skeletal adaptations that clearly demonstrated their upright walking abilities.

Australopithecus africanus possessed distinct features, such as larger molars, a robust mandible, and a forward shift of the zygomatic arch, creating a wide and flat face. These adaptations indicate a powerful bite and increased use of cheek teeth.

The prominent zygomatic arch and canine pillars in Australopithecus africanus strengthened the chewing structures of the upper jaw. These modifications indicate a greater reliance on chewing, suggesting a dietary shift compared to earlier hominins.

Australopithecus africanus is considered a potential ancestor of the genus Paranthropus. It represents a potential early step in the evolution of hominins with specialized chewing adaptations.

Australopithecus sediba was discovered in Malapa Cave, South Africa, in 2008. Remains of two individuals, a young boy and an adult female, date back to about 2 million years ago. The boy's well-preserved skull revealed a cranial capacity of 420 cubic centimeters, similar to Australopithecus africanus, while both individuals were approximately 130 centimeters tall.

Australopithecus sediba's features, including its brain size and body proportions, suggest a potential link to the genus Homo. However, the fragmentation of the fossil remains makes it difficult to fully understand its evolutionary importance.

The position of the foramen magnum in Australopithecus sediba indicates a more upright posture than in apes, suggesting potential bipedalism. However, the fragmentation of the remains makes definitive conclusions about its locomotion difficult.

The inner ear bones of lambs show a resemblance to those found in apes, indicating an adaptation for climbing trees. This suggests that early hominins may have also climbed trees.

The shape of the inner ear bones indicates an adaptation for balancing, which can be important for both climbing and bipedal walking. In apes, the bones are shaped for arboreal locomotion, while in humans, they are adapted for bipedalism.

Ethiopicus, a hominin species, possessed a powerful bite force, comparable to a gorilla's, exceeding that of modern humans.

A large muscle attached to the side of the skull, extending towards the top in Ethiopicus, responsible for a strong bite force.

A prominent bony ridge on the top of the skull where the temporalis muscles meet, indicating a large muscle attachment.

The cheekbone, which supports the masseter muscle, contributing to increased bite force.

A powerful muscle attached to the cheekbone, responsible for chewing and increasing bite force.

Ethiopicus is considered a potential ancestor for two later hominin species, Paranthropus boisei and robustus.

A diagram showing the evolutionary relationships between different hominin species, tracing their ancestry and common ancestors.

Two early hominin species, closely related, considered potential ancestors for later human lineages.

Paranthropus, especially P. boisei and P. robustus, had extremely large molars, significantly larger than any other hominin. This trait is known as megadontia.

While initially thought to subsist solely on hard nuts and plants, recent analysis suggests Paranthropus had a more varied omnivorous diet, likely including some meat, but primarily fibrous plant food, similar to gorillas.

Both P. boisei and P. robustus made and used simple stone tools, indicating some level of technological capability.

Paranthropus, like the Australopithecines, exhibited significant sexual dimorphism. Males had larger skulls, brains, and a pronounced sagittal crest compared to females.

The Paranthropus lineage appears to be an evolutionary dead end, with no known descendants. Their specialized adaptations likely contributed to their eventual extinction.

Generalized species are adaptable to a wider range of environments and diets. They can thrive in different conditions but may not be perfectly suited to any one specific environment.

Specialized species are adapted to very specific conditions and diets. They thrive in their specific niche but struggle to adapt to changes in their environment.

Generalized species, because of their adaptability, tend to survive longer, especially in changing environments. Specialists often die out when their specific niche disappears.