HOME >> BIOLOGY >> NEWS
Gondwana split sorts out mammalian evolution

Placental mammals are a diverse group, with nearly 4000 described species (e.g., rodents, bats, elephants, humans) that bear live young and are nourished before birth in the mother's uterus through the placenta. In contrast, marsupials are commonly thought of as pouched mammals. While the latter also give live birth, they do not have long gestation times; the early development is completed instead in the pouch.

Although independent studies have resolved placental mammals into four major groups, it is not clear what the hierarchical relationships within the groups are, thus hampering the understanding of the early biogeographic history of placentals. The four major groups are:

(1) Afrotheria [elephants, hyraxes, manatees and dugongs, aardvarks, golden moles, tenrecs, and elephant shrews],

(2) Xenartha [armadillos, anteaters, and sloths],

(3) Laurasiatheria [carnivores (e.g., bears, cats, dogs), pangolins, whales and dolphins, even-toed ungulates (e.g., hippos, cows, pigs), odd-toed ungulates (e.g., horses, rhinos), bats, and insectivores (e.g., shrews, moles, hedgehogs)], and

(4) Euarchontoglires [rodents, rabbits, tree shrews, flying lemurs, and primates (e.g., humans, monkeys, lemurs)].

In the 14 December 2001 issue of Science, a team of scientists discuss alternative positions for the root of the placental tree. They report results based on Bayesian and other statistical methods and use a data set that comprises approximately 16,400 base pairs for each of 44 mammals and that includes segments from 22 different genes. "We have resolved the interordinal relationships almost entirely," says Mark S. Springer of the University of California, Riverside, a member of the team. "Based on molecular clocks, we found that the deepest split occurs between Afrotheria and other placentals at ~103 million years, a date that coincides with a major plate tectonic separation."

The result is controversial. Some research
'"/>

Contact: Iqbal Pittalwala
iqbal@citrus.ucr.edu
909-787-2645
University of California - Riverside
18-Jan-2002


Page: 1 2

Related biology news :

1. Two dinosaurs from Africa give clues to continents split
2. Seeing how plants split water could provide key to our future energy needs
3. Americans knowledge of genetically modified foods remains low and opinions on safety still split
4. Poll: NY residents split on biotechnology in food and agriculture
5. Fast changing gene drives species split
6. Tiny tango: Device sorts microscopic particles with speed and precision
7. Gene-based screen sorts cancer cases, say Stanford researchers
8. UCLA researchers recreate patterns formed by mammalian cells
9. Gametes and embryos from mammalian stem cells: religious and ethics perspectives
10. Knocking the Sox off early mammalian development
11. Rockefeller researchers provide the first functional evidence for mammalian pheromone receptors

Post Your Comments:
*Name:
*Comment:
*Email:


(Date:7/31/2018)... ... July 31, 2018 , ... GSL Biotech ... with LabArchives , the leading cloud-based Electronic Lab Notebook (ELN) platform. , ... researchers to store all of their research data records in a secure, compliant online ...
(Date:7/29/2018)... ... 29, 2018 , ... Dr. William Plikerd, an evidence-based energy healer, today announces ... immunity and to combat inflammation and autoimmune disorders. , The preclinical research assessed ... reported:, Up to 260% increase overall immunity as seen ...
(Date:7/26/2018)... ... July 25, 2018 , ... Boston Biotech Conferences will ... 4, 2018 at The Hilton Boston Back Bay Hotel. This peer-to-peer meeting provides ... and dissect the most relevant deals in biotech. , George Golumbeski recently joined ...
Breaking Biology News(10 mins):
(Date:8/7/2018)... ... August 06, 2018 , ... Slone Partners, ... the placement of Dr. Paul Harney as President, North America at Prescient Healthcare ... and enhancing client satisfaction. He was also named to Prescient’s Board of Directors. ...
(Date:7/31/2018)... ... July 31, 2018 , ... ... years, announces the launch of their new website. The new website has been ... the site. Mahoney partnered with Proceed Innovative to build a website created for ...
(Date:7/25/2018)... ... July 25, 2018 , ... Vium, Inc. ... Digital Vivariumâ„¢ and Vium Cloud approach to accelerate preclinical drug discovery and development, ... the company announced the appointment of Jeff Caron to the newly formed role ...
(Date:7/24/2018)... ... July 24, 2018 , ... R3 Stem Cell is now offering regenerative therapies ... offered by Double Board Certified providers, with outcomes significantly improving patient quality of life. ... have done nothing to help repair and regenerate damaged lung tissues. Stem cell ...
Breaking Biology Technology:
Cached News: