Meet Our newest Ancestors Homo Naledi

                                                    Homo Naledi
Domain : Eukarya
Kingdom : Animalia
Phylum : Chordata
Subphylum : Vertebrata
Class : Mammalia
Order : Primates
Family : Hominidae
Sub Family : Homininae
Tribe : Hominini
Subtribe : Hominina
Genus : Homo
Species : Homo Naledi

A team of Paleoanthropologists under Lee Berger went into the Rising Star Cave in Gauteng Province in South Africa in 2013 and till 2016 fossils were found there and these fossils have been proposed to represent he extinct species of the hominin Homo Naledi.

 The Rising Star Cave











The excavation team consisted six paleoanthropologists who were all female and could pass through an openeing only seven inches ( 18 cm ) wide to acess the Dinaledi chamber. Those chosen were Hannah Morris , Marina Elliot , Becca Peixotto , Alia Gurtov , Lindsay Eaves and Ellen Feuerriegel.
They have since been named the Underground Astronauts .
More than 1200 fossils were found in the Dinaledi Chamber and catalouged in November 2013 representing atleast a dozen individuals . Only 20 out of 206 bones of the human body were not found in the chamber.

As of September 2015 fossils of atleast 15 individuals , amounting to 1550 specimens , had been excavated from the cave. About 300 bone fragments were found from the surface of the Dinaledi  Chamber  and about 1250 fossil specimens  were recovered from the chamber's excavation pit . The fossils include skull ,jaws , ribs , teeth , bones of an almost complete foot , of a hand and of an inner ear. The bones of old , young and infant individuals were found .

ARTISTS IMPRESSION OF THE HOMO NALEDI

Anthropologist John D Hawkes from the University of Wisconsin Madinson who was a member of the team stated that the scientific facts are that all bones recovered are hominid except for those of an owl. There is no sign of predation and and there is no predator that  accumulates  only hominids this way and the bones were not accumulated here all at once . There is no evidence of rocks falling into the cave along with the  bones or the bones having been flown here along with water . Lee Berger and his team have suggested that the best hypothesis that these individuals were capable of ritualistic behaviour . They speculate that the placing of dead bodies in the cave was a ritualistic behaviour , a sign of symbolic thought which implies that they had intelligence and were similar to human species

The homo naledi fossils are the largest collection of fossils found of a single species of hominin in Africa and provides information about the early evolution of humans.



Picture Right - Skeletons Discovered

Decline of Early Crocodile Helped the Early Marine Turtle

Marine turtles experienced an evolutionary windfall thanks to a mass extinction of crcodyliforms around 145 million years ago. 

Crocodyliforms comprise modern crocodiles and alligators and their ancient ancestors, which were major predators that thrived on Earth millions of years ago. They evolved into a variety of species including smaller  ones that lived on land through to mega-sized sea-swimming species that were up to 12 metres long. However, around 145 million years ago crocodyliforms, along with many other species, experienced a severe decline -- an extinction event during a period between two epochs known as the Jurassic/Cretaceous boundary. 

During this boundary up to 80 percent of species on land and in marine environments were wiped out . This decline was primarily due to a drop in sea level, which led to a closing off of shallow marine environments such as lagoons and coastal swamps. These were the homes and primary hunting grounds for may crocodyliforms. The decimation of many marine crocodyliforms may also have laid the way for their ecological replacement by other large predatory groups such as modern shark species  and new types of plesiosaurs. Plesiosaurs were long-necked, fat-bodied and small headed ocean-going creature with fins, which later went extinct around 66 million years ago.

Other factors that contributed to the decline of marine crocodyliforms included a change in the chemistry of ocean water with increased sulphur toxicity and a depletion of oxygen. While primitive crocodilyform species on land also suffered major declines, the remaining species diversified into new groups such as  the new extinct notosuchians, which were much smaller in size at around 1.5 metres in length. Eusuchians also came to prominence after the extinction which led to today's crocodiles.

For this research work the researchers analyzed almost 1,200 crocodyliforms fossil records.

Source: Biological Science

Mass Extinction can Wiped Out Any Species

There have been five mass extinction events in the Earth's history, including climate change caused by volcanoes and an asteroid hit that wiped out the dinosaurs. In general, geographically widespread animals are less likely to become extinct than animals with smaller geographic ranges, offering insurance against regional environmental catastrophes. 

However, a study published in the Nature has found this insurance is rendered useless during global mass extinction events and  that widely distributed animals are just as likely to suffer extinction as those that are less widespread. 

The researchers explored the fossil record of terrestrial vertebrate (including dinosaurs) from the Triassic and Jurassic periods (252 - 145 million years ago).

Source: University of Leeds