OHS2020 Chap2
How to date fossil remains?
There are two ways to date fossil remains: relative dating and physical dating.
The first method calculates the layers and the origin of the deposits on the fossil.
The second method uses natural clocks (that use physical properties) to calculate how much time has passed since the organism has died.
The most famous method is called radiocarbon dating which detects carbon-14 (which is a form of carbon). By measuring the amount of carbon-14 left in the deceased organism, we can determine when the organism died. Another technique that combines relative and physical dating is palaeomagnetism. It uses the Earth's magnetic poles and the position at which they were when the organism died, allowing us to calculate at which period of time that was. --LiljaP
Nice but please, sign so we know who wrote this textPierre.brawand (discussion) 30 mars 2020 à 16:43 (CEST)
How do we know that Orrorin tugenensis was a hominin?
The main proof is found by looking at the shape and anatomical features of the leg bones. The femur of Orrorin tugenensis ressembles that of Australopithecus and other fossil apes from the Miocene with its unique shape, i.e. a long and flat femoral neck, implying that it was a bipedal. However, the dentition and powerful arms of Orrorin tugenensis indicate some similarities with apes, which leaves somewhat of a nuance to this argument. --GavinC (discussion) 30 mars 2020 à 16:43 (CEST)
GoodPierre.brawand (discussion) 30 mars 2020 à 16:44 (CEST)
Who is Ardi and what are her specificities?
Ardi is the nickname given to an almost completed female skeleton. She belongs to the species of Ardipithecus ramidus. Palaeoanthropologists have discovered a set of teeth and more than 100 fossil fragments. The skeleton of Ardi reveals many anatomical characteristics. First, many features show that the organsim could move in a bipedal way and at the same time, it shows features really close to the ones in many apes (strong leg muscles that help to climb trees). Ardi also has hands that don't seem really adapted for climbing. Her feet on the other hand are not well adapted for walking but practical for climbing and grabbing tree branches. This species shows also a little difference in the anatomy of male and female organisms. The males were a bit bigger and their canines were also slighlty larger than the females. --LiljaP
Nice Lilja but please sign your text with the right signature.Pierre.brawand (discussion) 31 mars 2020 à 21:53 (CEST)
What are the main differences between the three different genera: Sahelanthropus, Orrorin and Ardipithecus?
The main differences are that the "Sahelanthropus" lived in central Africa and were very close to the divergence of the chimpanzee and the human lineages. The "Sahelanthropus" fossils were approximately 6-7 milion years old and was the most primitive hominin. They had an upright walking and a prominent brow ridge above the eye orbits. The "Orrorin" fossil that were found dated at around 5.7-6 milion years in the region of Kenya. They had a bipedal walking and lived in the threes. The "Ardipithecus" lived in the middle Awash region of Ethiopia. Their upper part of the pelvis was shorter than those of living apes. They had a bipedal walking and their hand and feets features ressembling neither to chimpanzees nor humans. --EmmaMC (discussion) 7 avril 2020 à 10:55 (CEST)
What is biochronology and how does it work ?
Biochronology is a technic which consists in comparing and matching the different types of animals found in an undated fossil assemblages with similar fossil assemblages from other sites that have already been dated. That way the age of different fossils can be determined and therefore the age of different species too! This was done with Sahelanthropus fossils which were estimated to be 6 to 7 million years old. --VictoriaW (discussion) 2 avril 2020 à 19:30 (CEST)
What does Computerized Tomography allow and how is it relevant ?
Computerized Tomography (CT scan) combines a series of X-ray images taken from different angles around a fossil.
CT scans are also widely used in modern medicine, not only for fossils.--Pierre.brawand (discussion) 7 avril 2020 à 10:37 (CEST)
It uses computer processing to create cross-sectional images which allows to visualize a fossil without any cracks and deformation that may be present in the original fossil (due to damage endured over time probably). This is relevant because scientists can study more precisely the different fossils. --VictoriaW (discussion) 2 avril 2020 à 19:54 (CEST)
What did we learn from Sahelanthropus fossils ?
Several Sahelanthropus fossils have been found in the Djurab desert in Chad.They represented at least six different individuals. Before this discovery, the earliest known hominins had only be found in eastern Africa. This new species revealed that the earliest hominins were much more widely distributed across Africa than what was thought. Fossils from a diverse range of mammals, reptiles and fish were found at the same site. These indicates that this recently discovered hominin was living in an environment surrounded by different habitats like forests growing along rivers, wooded savannah and grassland, instead of the Djurab desert.--MicheleM (discussion) 6 avril 2020 à 17:40 (CEST)
- retour à Our_Human_Story_2020
- retour à Accueil