...
Post A Reply
my profile
|
directory
login
|
register
|
search
|
faq
|
forum home
»
EgyptSearch Forums
»
Deshret
»
Some interesting articles
» Post A Reply
Post A Reply
Login Name:
Password:
Message Icon:
Message:
HTML is not enabled.
UBB Code™ is enabled.
[QUOTE]Originally posted by DD'eDeN: [QB] Rise of East African Plateau dated by whale fossil Old bones' elevation constrains timing of uplift that influenced human evolution Ashley Yeager 2015 A 17-Ma whale fossil is helping scientists pinpoint when the E.African Plateau started to rise. Determining when the uplift happened has implications for understanding human evolution, scientists say. Shifts in the Earth's mantle pushed the E.African Plateau upward between 17 & 13.5 Ma. <http://www.pnas.org/cgi/doi/10.1073/pnas.1421502112> Their analysis was based on a Turkana ziphiid fossil, discovered at the edge of the plateau in Kenya in 1964. The beaked whale's skull was described in a 1975 paper, then misplaced until 2011, when it was rediscovered in a fossil collection kept at Harvard. (Moroto, Uganda, where Morotopithecus ?17 Ma was found (the first eu-hominoid?), is now at 1380 m above sea-level --mv) A 17-My-old whale constrains onset of uplift and climate change in east Africa Henry Wichura cs 2015 PNAS 112 An enigmatic fossil of the deep-diving open-ocean whale family Ziphiidae, 740 km inland, at 620 m elevation in West Turkana, Kenya was re-discovered, after it went missing for >30 yrs. This stranded whale fossil provides the first constraint on the initiation of E.African uplift from near sea level at 17 Ma, limiting the timing & initial elevation of environmental change indicated by geo-dynamic & climatic modeling, paleo-sols, isotopes, paleo-botany & the mammalian fossil record. At 17 Ma, - elevation was low, - rainfall was high, - vegetation was forested, - mammalian communities contained immigrants & native African spp incl.diverse primates. Uplift resulted in increasing aridity & open habitats that drove human evolution. Timing & magnitude of surface uplift are key to understanding the impact of crustal deformation & topographic growth on atmospheric circulation, environmental conditions & surface processes. Uplift of the E.African Plateau is linked to mantle processes, but paleo-altimetry data are too scarce to constrain plateau evolution & subsequent vertical motions associated with rifting. Here, we assess the paleo-topographic implications of a beaked whale fossil from the Turkana region, found 740 km inland from the present-day coastline of the Indian Ocean, at an elevation of 620 m. The specimen is ?17 My old, it represents the oldest derived beaked whale known, consistent with molecular estimates of the emergence of modern strap-toothed whales Mesoplodon. The whale traveled from the Indian Ocean inland along an east-ward-directed drainage system controlled by the Cretaceous Anza Graben, it was stranded slightly above sea-level. Surface uplift from near sea-level coincides with paleo-climatic change - from a humid environment - to highly variable & much drier conditions, this altered biotic communities, and drove evolution in E.Africa, including that of primates. [/QB][/QUOTE]
Instant Graemlins
Instant UBB Code™
What is UBB Code™?
Options
Disable Graemlins in this post.
*** Click here to review this topic. ***
Contact Us
|
EgyptSearch!
(c) 2015 EgyptSearch.com
Powered by UBB.classic™ 6.7.3