Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, India

Fossil site in Kerala, India

Fossil wood park maintained by geological survey of India at Tamilnadu

Cretaceous fossil sites india

Fossils in rack:-Cyad

Fossils in rack:-echiniderms

Fossils in rack:-Rastellum sp

Pre-historic seabed, Cretaceous period

New fossils show that four different types of birds had stiff feathers on their legs.

March 18th, 2013 Riffin

More than 100 million years ago, birds living in what is now China sported wings on their legs, a new study of fossils suggests.

Researchers found evidence of large leg feathers in 11 bird specimens from China’s Shandong Tianyu Museum of Nature. The feathers suggest that early birds had four wings, which may have played a role in the evolution of flight, scientists report in a study published today (March 14) in the journal Science.

Most scientists believe that birds evolved from other feathered dinosaurs; this belief is supported by discoveries of fossils of feathery birdlike creatures. In 2000, scientists discovered a nonavian dinosaur with feathers on its arms and legs, called Microraptor, which could probably fly. In addition, specimens of Archaeopteryx, a transitional fossil between modern birds and feathered dinosaurs, show faint featherlike structures on their legs, but the signs are poorly preserved.

Chinese fossils reveal that ancient birds had feathers on their legs, prompting some to call them four-winged birds. Some scientists think these wings helped the birds to fly, while others think they were used in courtship. Science/AAAS/LiveScience

Chinese fossils reveal that ancient birds had feathers on their legs, prompting some to call them four-winged birds. Some scientists think these wings helped the birds to fly, while others think they were used in courtship.
Science/AAAS/LiveScience

Now, leg feathers have been spotted in the 11 museum fossils that had been collected from the Lower Cretaceous Jehol formation in Liaoning, China, from a period about 150 million to 100 million years ago. The feathers are stiff and stick straight out from the birds’ legs, and have a large enough surface area to be aerodynamic, the researchers say.

The fossils belong to at least four different groups, including the genera Sapeornis, Yanornis and Confuciusornis, as well as the Enantiornithes group. The findings suggest that leg feathers weren’t just an evolutionary rarity.

The researchers also analyzed feathers of other birds and nonbird dinosaurs. Feathers covering the entire leg and feet first developed in dinosaurs, continued in early birds and later disappeared, the results imply. Birds gradually lost feathers on their feet and then their legs, and today, modern birds have wings on their arms only.

Whether these early birds used their leg feathers to fly, and how they may have done so, is up for debate. According to the study researchers, the flat surface formed by the stiff perpendicular feathers could have provided lift and maneuverability. 

“These new fossils fill in many gaps in our view of the early evolution of birds,” animal flight expert David Alexander of the University of Kansas, Lawrence, who was not involved in the study, told Science magazine. Alexander agrees that the feathers probably had some aerodynamic function, “although whether as stabilizers, steering vanes, or full-blown wings remains to be seen.”

Other scientists aren’t convinced. Paleontologist Kevin Padian of the University of California, Berkeley, told Science that the authors don’t provide evidence that the feathers contributed to any sort of flight. In fact, the feathers would create drag that would hinder flight, Padian said. The birds may have used their plumes for courtship instead, another scientist suggested.

More studies are needed to nail down the feathers’ function. Examining more fossils from the thousands in the museum collection will help, the study’s authors say.

Dinosaur-Era Climate Change Study Suggests Reasons for Turtle Disappearance

March 17th, 2013 Riffin

The dry, barren prairie around Alberta’s Drumheller area was once a lush and subtropical forest on the shores of a large inland sea, with loads of wetlands inhabited by dinosaurs, turtles, crocodiles and small mammals.

But that changed about 71-million-years ago, according to a new study by researchers Annie Quinney and Darla Zelenitsky in paleontology at the University of Calgary. The researchers’ calculations show that drastic climate change occurred during a five-million-year period in Alberta’s badlands. At this time, the wetlands dried up and the warm humid climate was interrupted by a sudden cool, drying spell.

The study of ancient climate change is important as it helps researchers understand the impact sudden heating and cooling may have had on plants and animals.

“This was a time of change in Alberta, the wetlands disappeared as the inland sea retreated and the climate cooled,” says Quinney, a former master’s student in the Department of Geoscience. She led the study recently published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology, which was part of her master’s degree in the Department of Geoscience.

Dramatic climate change was previously proposed to be responsible for the disappearance of turtles 71-million-years ago, because they were considered to be “climate-sensitive” animals. Results of this research, however, show that the disappearance of turtles came before the climate cooled and instead closely corresponds to habitat disturbances, which was the disappearance of wetlands.

This shows Annie Quinney excavating ancient soils in 70 million-year-old rocks in the Drumheller badlands. (Credit: Credit: Kohei Tanaka, University of Calgary.)

This shows Annie Quinney excavating ancient soils in 70 million-year-old rocks in the Drumheller badlands. (Credit: Credit: Kohei Tanaka, University of Calgary.)

“The big surprise is that some animals, for example turtles, appeared to be more sensitive to habitat disturbances than to climate changes. Therefore, even if climatic conditions are ‘ideal,’ turtles may disappear or may not recover unless habitats are just right,” says Quinney.

Quinney and supervisors Zelenitsky, assistant professor in the Department of Geoscience, and François Therrien of the Royal Tyrrell Museum in Drumheller studied ancient soils preserved in the rocks in the Red Deer River valley near Drumheller that were deposited 72 to 67 million years ago and record information about the past climate and environments.

Researchers calculated precipitation and temperature levels over a five-million year interval and during that time, temperature and precipitation dropped over a few thousand years, and that cooler interval lasted for 500,000 years.

“By studying the structure and chemistry of ancient soils, we were able to estimate the ancient temperature and rainfall that prevailed when those soils formed millions of years ago,” says Quinney, who is now completing a PhD at Monash University in Australia on a full scholarship.

Mineral Shows in March 2013

March 16th, 2013 Riffin

March 16-17—SAN ANTONIO, TEXAS

Southwest Gem & Mineral Society; San Antonio Event Center; 8111 Meadow Leaf Dr.; Sat. 10-6, Sun. 10-4; adults $5, seniors and military $3, students $2, children $1; minerals, fossils, jewelry, gemstones, club exhibits, silent auction, children’s games, hourly and grand door prizes; contact Robert Bowie, TX 78133, (210) 287-5233; e-mail: krbotx@gvtc.com; Web site: www.swgemandmineral.org

March 16-17—VISTA, CALIFORNIA

Palomar Gem & Mineral Club; Antique Gas & Steam Engine Museum; 2040 N. Santa Fe Ave.; Sat. 9-5, Sun. 9-4; free admission; displays, dealers, gems, mineral, fossils, jewelry, door prize, general store, demonstrations, children’s activities; contact Diane Hall, 528 Shadywood Dr., Escondido, CA 92026, (760) 741-0433; e-mail: dhall13@cox.net; Web site: www.palomargem.org

March 15-16-COTTONWOOD, ARIZONA

Val Latham and Sharon Szymanski; Mingus Union High School; 1801 E. Fir St.; Fri. 10-5, Sat. 9-4; adults $3, children (under 12) free with adult; dealers, minerals, rocks, copper, beads, fine and costume jewelry, unset gemstones, fossils, cabochons, lapidary machinery and supplies, wire wrapping on the premises; contact Val Latham, 840 W. Charleston Ave., Phoenix, AZ 85140, (602) 350-1756; e-mail: val65@cox.net

March 15-17-ALBUQEURQUE, NEW MEXICO

Albuquerque Gem & Mineral Club; Albuquerque State Fairgrounds, Expo NM; 300 San Pedro NE, enter from San Pedro at Copper St.; Fri. 10-6, Sat. 10-6, Sun. 10-5; adults $3, $1 Fri., children (under 13) free; 45 dealers, exhibits, minerals, fossils, jewelry, crystals, cut stones, displays, books, raffles, silent auction, door prizes, Creative Arts Center; contact Paul Hlava, (505) 265-4178; e-mail: paulhlava@q.com; Web site: www.agmc.info

March 15-17-JACKSON, MICHIGAN:

niors $2, students $1, children (under 5),military personnel, police, firefighters, and Scouts in uniform free; junior activities, gems, minerals, meteorites, fossils, beads, jewelry, demonstrators, silent auctions, displays, gold panning, door prizes; contact Sally Hoskin, 10990 Phal Rd., Grass Lake, MI 49240, (517) 522-3396; e-mail: saltoosal2@yahoo.com; Web site: www.mgmsrockclub.com

March 15-17-KANSAS CITY, MISSOURI

Greater Kansas City Association of Earth Science Clubs; KCI Expo Center; 11730 NW Ambassador Dr.; Fri. 9-8, Sat. 10-7, Sun. 10-5; adults $6, children (5-12) $3; contact Mark Sherwood, PO Box 436, Oak Grove, MO 64075, (816) 690-8226; e-mail: kcgsinfo@yahoo.com; Web site: www.kcgemshow.org

March 15-17-ROME, GEORGIA

Rome Georgia Mineral Society; The Forum; 301 Tribune St.; Fri. 10-6, Sat. 10-6, Sun. 11-5; free admission; minerals, gems, fossils, jewelry, crystals, mineral identification, door prizes, exhibits; contact Jose Santamaria, 311 E. 4th St., Rome, GA 30161, (678) 488-9560; e-mail: rogams.show@gmail.com; Web site: http://rogams.wordpress.com/gem-and-mineral-show/

March 15-17-SPANISH FORK, UTAH

54th “Spring Parade of Gems”; Timpanogos Gem & Mineral Society; Spanish Fork Fair Grounds; 475 S. Main; Fri. 10-7, Sat. 10-7, Sun. 10-5; free admission; displays, dealers, jewelry, fossils, equipment, Mr. Bones, door prizes, touch table, rock sales, silent auction, rocks in the rough, minerals, lapidary equipment, Junior Club Booth, kids’ grab bags, Wheel of Fortune, instruction on polishing cabochons, demonstrations, faceting, knapping, wire wrapping, beading, fluorescent mineral display; contact Keith Fackrell, 2295 East 700 South, Springville, UT 84663, (801) 592-0410; e-mail: timprocks@gmail.com; Web site: http://timprocks.weebly.com

The rocks and minerals pictured above are from different parts of Kansas.

The rocks and minerals pictured above are from different parts of Kansas.

March 16-17-CEDAR RAPIDS, IOWA

Cedar Valley Rocks & Minerals Society; Hawkeye Downs Expo Center; 4400 6th St. SW; Sat. 8:30-6, Sun. 9:30-5; adults $2, students (12-18) $1, children (under 12) and youth groups with adult free; Iowa fossils, Tarbosaur Skeleton, 7-inch shark jaw, educational programs, demonstrations, dealers, children’s activities, gem sluice; contact Marvin Houg, (319) 364-2868; e-mail: m_houg@yahoo.com; Web site: www.cedarvalleyrockclub.org

March 16-17-GAITHERSBURG, MARYLAND

49th annual show and sale; Gem, Lapidary & Mineral Society of Montgomery County; Montgomery County Fairgrounds; 16 Chestnut St.; Sat. 10-6, Sun. 11-5; adults $6 (coupon on Web site), children (under 12) and Scouts in uniform free; 22 dealers, gems, jewelry, minerals, fossils, more than 40 exhibits, demonstrations, free cabochon-polishing workshop, door prizes, raffles, kids’ table with free specimens, fluorescent display, mini-mine; contact Mark Dahlman, 11906 Scovell Terrace, Germantown, MD 20874; e-mail: showchair@glmsmc.com; Web site: www.glmsmc.com

March 16-17-LEMOORE, CALIFORNIA

Lemoore Gem & Mineral Club; Trinity Hall; 470 Champion St.; Sat. 10-6, Sun. 10-4; free admission; agate and jasper from around the world, fluorescent mineral display, lapidary rough and supplies, gems, minerals, beads, fossils, jewelry, stone carvings, reference books, rock-cutting demonstrations; contact Chris Wertenberger, PO Box 455, Lemoore, CA 93245-0455, (559) 309-3433

March 16-17-SEATTLE, WASHINGTON

North Seattle Lapidary & Mineral Club; Lake City Community Center; 12531 28th Ave. NE; Sat. 10-5, Sun. 10-5; free admission; junior activities, displays, demonstrations, dealers, club group project; contact Susan Gardner, (425) 483-2295; e-mail: sgardner3@mindspring.com; Web site: www.NorthSeattleRockClub.org

March 16-17-VALLEJO, CALIFORNIA

Vallejo Gem & Mineral Society; Solano County Fairgrounds, Mc Cormick Hall; 900 Fairgrounds Dr.; Sat. 10-5, Sun. 10-5; adults $5, children (under 14) free with adult; dealers, beads, crystals, opals, jade, turquoise, meteorites, door prizes, silent auction, wheel of fortune; contact Dan Wolke, 900 Fairgrounds Dr., Civic Bldg., Vallejo, CA 94589, (707) 745-1816; e-mail: dncwolke@sbcglobal.net; Web site: vallejogemandmineral.com

March 22-23-YUMA, ARIZONA

Sharon Szymanski; Yuma Civic Center; 1440 Desert Hills Dr.; Fri. 10-5, Fri. 9-4; adults $3, children (under 12) free with adult; indoor gem and jewelry show, dealers, minerals, fossils, rough, slabs, fine and costume jewelry, beads, copper, unset gemstones, lapidary equipment and supplies, wire wrapping on the premises; contact Sharon Szymanski, 1792 E. Laddoos Ave., San Tan Valley, AZ 85140, (480) 215-9101; e-mail: goldcanyon2@yahoo.com

March 22-24-HICKORY, NORTH CAROLINA

43rd annual show; Catawba Valley Gem & Mineral Club; Hickory Metro Convention Center; I-40 Exit 125; Fri. 9-6, Sat. 9-6, Sun. 10-5; adults $4, students and children free; exhibits, demonstrations, cabbing, faceting, tumbling, kiddie corner; contact Baxter Leonard, 2510 Rolling Ridge Dr., Hickory, NC 28602, (828) 320-4028; e-mail: gailandbaxter@aol.com

March 22-24-INDIANAPOLIS, INDIANA

15th Annual Spring Show; Treasures Of The Earth Gem & Jewelry Shows; Indiana State Fairgrounds; Agriculture/Horticulture Bldg., 1202 E. 38th St.; Fri. 10-6, Sat. 10-6, Sun. 11-5; adults $5 (3 days), children (under 16) free; beads, pearls, gemstones, wire wrapping, wire sculpture, silversmiths and goldsmiths, custom work and repairs while you wait, door prizes, classes available; contact Van Wimmer Sr., 5273 Bradshaw Rd., Salem, VA 24153, (540) 384-6047; e-mail: van@toteshows.com; Web site: www.toteshows.com

March 22-24-LOVELAND, COLORADO

52nd annual show; Fort Collins Rockhounds; The Ranch (Larimer County Fairgrounds); McKee Bldg., 5280 Arena Circle; Fri. 4-8, Sat. 9-6, Sun. 10-5; adults $4 (1 day, or $7 (3 days), students (12-18) with ID $1, children (under 12) free with adult; agates and calcite featured, exhibits, door prizes, grab bags, silent auction, demonstrations, gem and mineral dealers; contact Dee Spaulding, 2506 Pear Court, Fort Collins, CO 80521, (970) 493-6168; e-mail: fcrockhounds@yahoo.com; Web site: fortcollinsrockhounds.org

March 22-24-PORTLAND, OREGON

Mt. Hood Rock Club; Kliever National Guard Armory; 10000 NE 33rd Dr.; Fri. 10-5, Sat. 10-5, Sun. 10-4; free admission, donations accepted; contact L. Smith, (503) 646-1932; e-mail: mhrcshowchair@gmail.com

March 23-24-ANGELS CAMP, CALIFORNIA

Calaveras Gem & Mineral Society; Calaveras County Fairgrounds (Frogtown); 101 Frogtown Rd.; Sat. 10-5, Sun. 10-4; adults $4, children (under 12) free with adult; jewelry, gemstones, beads, fossils, meteorites, rocks, tools, minerals, kids’ area, silent auction, raffle, door prizes; contact Anna Christiansen, 245 N. 6th Ave., Oakdale, CA 95361-3124, (209) 847-1173; e-mail: achrist361@sbcglobal.net; Web site: calaverasgemand mineral.org

March 23-24-CHAMBERSBURG, PENNSYLVANIA

Franklin County Rock & Mineral Club; Hamilton Heights Elementary School; 1589 Johnson Rd.; Sat. 10-5, Sun. 10-4; adults $4, children (under 12) free with adult; jewelry, gemstones, minerals, fossils, displays, door prizes; contact Mike Mowen, 5979 Altenwald Rd., Waynesboro, PA 17268, (717) 264-9024; e-mail: mlmo@innernet.net

March 23-24-DES PLAINES, ILLINOIS

48th Annual Jewelry, Gem, Fossil, Mineral & Lapidary Show; Des Plaines Valley Geological Society; Des Plaines Park District; 2222 Birch St.; Sat. 9:30-5; adults $3, seniors $2, students $1, children (under 12) free with adult; kids’ room, silent auction, demonstrations, raffles, dealers, fine gems and jewelry; contact Lois Zima, (847) 298-4659; e-mail: KSCHUSTER921@AOL.com

March 23-24-HAMBURG, NEW YORK

Buffalo Geological Society; The Fairgrounds; S. Park Ave.; Sat. 10-6, Sun. 10-5; adults $5, children (under 12) free; demonstrations, beads, jewelry, private gem collections, gifts, educational exhibits, drawings; contact Steve Bitrz, NY, (716) 773-6386; e-mail: sbirtz@aol.com; Web site: buffalogeological@gmail.com

March 23-24-NORTHAMPTON, MASSACHUSETTS

Western Mass Mineral Jewelry & Fossil Show; Connecticut Valley Mineral Club; Clarion Hotel & Conference Center; 1 Atwood Dr.; Sat. 9:30-5, Sun. 10-4; adults $5, children (12 and under) and Scouts in uniform free with adult; minerals, gemstones, jewelry, crystals, beads, fossils, lapidary and mineral arts, live demonstrations, free exhibits; contact Chris Wayne, (413) 529-0257; e-mail: cwayne@ed-tech.com; Web site: www.westernmassmineralshow.com

March 23-24-PORT ANGELES, WASHINGTON

City of Port Angeles; Vern Burton Community Center; 308 E. 4th St.; Sat. 9-6, Sun. 10-5; free admission; more than 35 dealers, free rock for kids while supplies last, raffle drawings, rough and polished rocks, giant thunder eggs, slabs, carvings, lapidary tools, beads, fused glass, faceted gemstones, faceting rough, crystals, fossils, minerals, beach glass, shells, jewelry, wire wrapping, woodworking, cabochons, equipment; contact Cindy Kochanek, 308 E. 4th St., PO Box 1150, Port Angeles, WA 98362, (360) 417-4550; e-mail: ckochane@cityofpa.us; Web site: www.cityofpa.us

March 23-24-SAYRE, PENNSYLVANIA

Che-Hanna Rock & Mineral Club; Athens Twp. Volunteer Fire Hall; 211 Herrick Ave.; Sat. 9-5, Sun. 10-4; adults $3, students $1, children (under 8) free; museum displays, kids’ activities, geode cutting, dealers, minerals, fossils, lapidary, jewelry, UVBob’s fluorescent show; contact Inga Wells, 502 Church St., Athens, PA 18810, (570) 731-4396; e-mail: ingawells@yahoo.com; Web site: www.chehannarocks.com

gold

gold

March 23-24-TORRANCE, CALIFORNIA

64th annual show and sale; South Bay Lapidary & Mineral Society; Ken Miller Recreation Center; 3341 Torrance Blvd., entrance on Madrona Ave.; Sat. 10-5, Sun. 10-4; free admission; door prizes, special guest exhibitors and demonstrators, fluorescent mineral show, petrified forest display, polished stones, slabs, rough rock, Artisans Store featuring handmade jewelry; contact Bill Sudduth, (310) 787-7851; e-mail: Sudduth3@msn.com; Web site: www.palosverdes.com/sblap

March 23-25-ROSEVILLE, CALIFORNIA

51st Annual Gem Show; Roseville Rock Rollers Gem & Mineral Society; Roseville (Placer County) Fairgrounds; 800 All America City Blvd., off Washington; Sat. 10-5, Sun. 10-4; adults $6, seniors $5 (coupon on Web site), children (12 and under) free; two huge buildings, more than 45 dealers, crystals, beads, gemstones, handcrafted jewelry, gold panning, fossils, meteorites, polished stones, opal, world-class mineral specimens, tourmaline, gold, sunstones, special kids’ activity area, free gem and mineral identification, demonstrations, silent auctions, more than 35 exhibits, raffle, hourly door prizes, lapidary shop open house; contact Gloria Marie, PO Box 1547, Foresthill, CA 95631, (916) 216-1114; e-mail: gloriarosevillerockrollers@gmail.com; Web site: www.rockrollers.com

March 29-30-COLVILLE, WASHINGTON

Panorama Gem & Mineral Club; Ag Trade Center; NE Washington Fairgrounds, 317 W. Astor Ave. (at Washington St.); Fri. 8:30-6, Sat. 9-5; free admission; donations for scholarship fund accepted; contact Bill Allen, (509) 936-5847; e-mail: sago@theofficenet.com

March 30-31-BELLINGHAM, WASHINGTON

Mt. Baker Rock & Gem; Bloedel Donovan Community Center; 2214 Electric Ave.; Sat. 10-6, Sun. 10-5; free admission; gold panning, lapidary demonstrations, fluorescent show, rocks, minerals, fossils, gems, jewelry, club sales, dealers, door prizes, scholarship raffle, silent auction, exhibits, special kids’ activities; contact Lori Nettles, (360) 961-7873; e-mail: lorinhardy@yahoo.com; Web site: www.mtbakerrockclub.org

March 30-31-SWEET HOME, OREGON

65th Annual Rock & Gem Show; Sweet Home Rock & Mineral Society; High School Gym; 1641 Long St.; Sat. 10-6, Sun. 10-5; adults 50 cents, children (12 and under) free; contact Joe Cota, PO Box 2279, Lebanon, OR 97355, (541) 451-2740

First Fossil Record of Alphonsea Hk. f. & T. (Annonaceae) from the Late Oligocene Sediments of Assam, India and Comments on Its Phytogeography

March 15th, 2013 Riffin

A new fossil leaf impression of Alphonsea Hk. f. & T. of the family Annonaceae is described from the Late Oligocene sediments of Makum Coalfield, Assam, India. This is the first authentic record of the fossil of Alphonsea from the Tertiary rocks of South Asia. The Late Oligocene was the time of the last significant globally warm climate and the fossil locality was at 10°–15°N palaeolatitude. The known palaeoflora and sedimentological studies indicate a fluvio-marine deltaic environment with a mosaic of mangrove, fluvial, mire and lacustrine depositional environments. During the depositional period the suturing between the Indian and Eurasian plates was not complete to facilitate the plant migration. The suturing was over by the end of the Late Oligocene/beginning of Early Miocene resulting in the migration of the genus to Southeast Asia where it is growing profusely at present. The present study is in congruence with the earlier published palaeofloral and molecular phylogenetic data. The study also suggests that the Indian plate was not only a biotic ferry during its northward voyage from Gondwana to Asia but also a place for the origin of several plant taxa.

Alphonsea leaves. A. Fossil leaf of A. makumensis sp. nov. showing shape, size and venation pattern. B. Modern leaf of A. lutea showing similar shape, size and venation pattern (Scale bar = 1 cm). doi:10.1371/journal.pone.0053177.g003

Alphonsea leaves.
A. Fossil leaf of A. makumensis sp. nov. showing shape, size and venation pattern. B. Modern leaf of A. lutea showing similar shape, size and venation pattern (Scale bar = 1 cm).
doi:10.1371/journal.pone.0053177.g003

 

Alphonsea leaves. A. Enlarged portion of the fossil leaf showing primary vein (red arrow), secondary veins (yellow arrows), brochidodromous venation (white arrows), random reticulate tertiary vein (blue arrow) and exmedial tertiary vein (orange arrow). B. Enlarged portion of the modern leaf of A. lutea showing similar primary vein (red arrow), secondary veins (yellow arrows), brochidodromous venation (white arrows), random reticulate tertiary vein (blue arrow), exmedial tertiary vein (orange arrow) and quadrangular areole (pink arrow). C. Enlarged portion of the fossil leaf showing primary vein (white arrow), secondary veins (red arrows) and intersecondary vein (yellow arrow). D. Modern leaf of A. lutea showing similar primary vein (white arrow), secondary vein (red arrows) and intersecondary vein (yellow arrow). E. Enlarged portion of the fossil leaf showing single quadrangular areole (yellow arrow) and free veinlets (red arrow). doi:10.1371/journal.pone.0053177.g004

Alphonsea leaves.
A. Enlarged portion of the fossil leaf showing primary vein (red arrow), secondary veins (yellow arrows), brochidodromous venation (white arrows), random reticulate tertiary vein (blue arrow) and exmedial tertiary vein (orange arrow). B. Enlarged portion of the modern leaf of A. lutea showing similar primary vein (red arrow), secondary veins (yellow arrows), brochidodromous venation (white arrows), random reticulate tertiary vein (blue arrow), exmedial tertiary vein (orange arrow) and quadrangular areole (pink arrow). C. Enlarged portion of the fossil leaf showing primary vein (white arrow), secondary veins (red arrows) and intersecondary vein (yellow arrow). D. Modern leaf of A. lutea showing similar primary vein (white arrow), secondary vein (red arrows) and intersecondary vein (yellow arrow). E. Enlarged portion of the fossil leaf showing single quadrangular areole (yellow arrow) and free veinlets (red arrow).
doi:10.1371/journal.pone.0053177.g004

 

Citation: Srivastava G, Mehrotra RC (2013) First Fossil Record of Alphonsea Hk. f. & T. (Annonaceae) from the Late Oligocene Sediments of Assam, India and Comments on Its Phytogeography. PLoS ONE 8(1): e53177. doi:10.1371/journal.pone.0053177

Editor: Subho Mozumdar, University of Delhi, India

 

Light Shed On Ancient Origin of Life

March 14th, 2013 Riffin

University of Georgia researchers discovered important genetic clues about the history of microorganisms called archaea and the origins of life itself in the first ever study of its kind. Results of their study shed light on one of Earth’s oldest life forms.

“Archaea are an ancient form of microorganisms, so everything we can learn about them could help us to answer questions about the origin of life,” said William Whitman, a microbiology professor in the Franklin College of Arts and Sciences and co-author on the paper.

Felipe Sarmiento, lead author and doctoral student in the microbiology department, surveyed 1,779 genes found in the genome of Methanococcus maripaludis, aquatic archaea commonly found in sea marshes, to determine if they were essential or not and learn more about their functions. He found that roughly 30 percent, or 526 genes, were essential. We now know which genes are driving the most important functions of the cell. The results of the study were published March 4 in the PNAS Early Edition and were performed with Jan Mrázek, an associate professor in the department of microbiology and the UGA Institute of Bioinformatics.

Archaea were first found in extreme environments, such as volcanic hot springs Pictured here is Grand Prismatic Spring of Yellowstone National Park. (Credit: By Jim Peaco, National Park Service [Public domain], via Wikimedia Commons)

Archaea were first found in extreme environments, such as volcanic hot springs Pictured here is Grand Prismatic Spring of Yellowstone National Park. (Credit: By Jim Peaco, National Park Service [Public domain], via Wikimedia Commons)

Although archaea are relatively simple organisms, the genetic systems they use to build cellular life are similar to those of more complicated eukaryotic cells found in complex organisms including animals and plants. For this reason, many scientists believe that eukaryotes evolved from ancient archaea.

These genetic systems are what allow information coded on DNA to build life.

“DNA by itself is a rock,” Whitman said. “You need all these other systems to make the DNA become a living cell.”

Because DNA is so fundamental to the modern cell, DNA synthesis has long been thought to be one of the most conserved processes in living organisms.

“It was a surprise when this study found that the system for making DNA was unique to the archaea,” Whitman said. “Learning that it can change in the archaea suggest that ability to make DNA formed late in the evolution of life. Possibly, there may be unrecognized differences in DNA biosynthesis the eukaryotes or bacteria as well.”

Other essential genes in these archaea are necessary for methane production. Methanogensis, or the process of making methane gas, is how these microorganisms make energy for life.

“Humans burn glucose and reduce oxygen to water, these guys burn hydrogen gas and reduce CO2 to methane,” Whitman explained.

Methanogenesis requires six vitamins not commonly found in other organisms. Understanding how these vitamins are made and how they are involved in the process of changing carbon dioxide to methane sheds light on developing new and better processes for methane production for fuel.

“This was a general investigation, but there are many questions it can answer, like possibly making methane better or more efficiently,” Whitman said.

The study yielded many other important results.

“We found 121 proteins that are essential for this organism that we know nothing about,” Sarmiento said. “This finding asks questions about their functions and the specific roles that they are playing.”

“We are starting to get some insights about how this organism was actually formed,” Sarmiento said. “There is a lot of information and it is interesting because it gives insights into a complete domain of life.”

Cryptic Clams: Biologists Find Species Hiding in Plain View

March 14th, 2013 Riffin

Cryptic comments seem to have an ambiguous, obscure or hidden meaning. In biology, cryptic species are outwardly indistinguishable groups whose differences are hidden inside their genes.

Two University of Michigan marine biologists have identified three cryptic species of tiny clams, long believed to be members of the same species, which have been hiding in plain view along the rocky shores of southern Australia for millions of years.

A closeup of L. australis clams from the southern Australia coast. Each clam is about the size of a rice grain. (Credit: Photo by Denis Riek)

A closeup of L. australis clams from the southern Australia coast. Each clam is about the size of a rice grain. (Credit: Photo by Denis Riek)

The unusual convergence of a climate-cooling event and the peculiarities of local geography caused the three cryptic species to split from a common ancestor more than 10 million years ago, the U-M researchers propose in a paper to be published next month in the journal Molecular Ecology.

The U-M scientists conducted a genetic analysis after collecting thousands of the crevice-dwelling, rice grain-sized clams from hundreds of miles of southern Australia coastline over the past decade. Their findings provide insights about the forces that shape evolution and solve a puzzle that has stumped marine biologists for decades.

“This study provides important clues about how marine regional biotas can evolve, including our observation that these processes can involve major global climate change modulated by local geography,” Jingchun Li, lead author of the report and a doctoral student in the U-M Department of Ecology and Evolutionary Biology.

Li conducted the research as part of her dissertation with co-author Diarmaid O’Foighil, Li’s adviser and director of the U-M Museum of Zoology.

“You cannot tell them apart physically, but their genes indicate that their evolutionary divergence predates that of humans from chimpanzees,” O’Foighil said of the three clam groups, which are currently classified as members of the same species, Lasaea australis.

Australia’s southern coastline is home to three evolutionarily distinct assemblages of marine species known as biogeographic provinces. Each province contains hundreds of species of invertebrates, fish, algae and other organisms, and there are substantial differences between the species living in each province.

Here’s the riddle that has perplexed biologists for decades: How did these three distinct biogeographic provinces evolve along a continuous coastline? The emergence of new species often begins when gene flow between populations is reduced or eliminated. This type of genetic isolation happened routinely throughout evolutionary history when populations became physically separated — when a new physical barrier such as a mountain or a river split the geographic range of a species, for example.

But what force could drive speciation along an unbroken coastline with no obvious barriers to gene flow?

The genetic analysis by Li and O’Foighil, which is backed by evidence from the fossil record, shows that the three cryptic clam species began splitting away from a common ancestor 13 or 14 million years ago.

That’s about the same time that a major climate-cooling event called the middle Miocene climate transition permanently lowered sea-surface temperatures in the southwest Pacific Ocean — including the southern coast of Australia — by 10.8 to 12.6 degrees Fahrenheit.

Li and O’Foighil propose that the cooling event partitioned Australia’s southern coastline into three zones with a cool region, including the present-day southeastern state of Victoria and the island of Tasmania, flanked on either side by two relatively warm ones.

The emergence of three temperature zones created opportunities for local adaptation that isolated the organisms living within each zone. That isolation led, in turn, to the evolution of the three biogeographic provinces seen today, according to Li and O’Foighil.

In their study, Li and O’Foighil showed that each of the three cryptic clam species is found in only one of the three biogeographic provinces.

“I know of no other case where you start out with one marine biota, then a climate-change event results in the generation of three biotas from that one,” O’Foighil said. “A key finding of the study is that relatively ancient climate-change events can shape marine biotas.”

fossil egg study :connection between French and Spanish dinosaurs

March 13th, 2013 Riffin

A study headed by the Miquel Crusafont Catalan Palaeontology Institute has for the first time documented detailed records of dinosaur egg fossils in the Coll de Nargó archaeological site in Lleida, Spain. Up until now, only one type of dinosaur egg had been documented in the region.

The archaeological site in Coll de Nargó containing dinosaur eggs lies some 8 kilometres to the west of the town that bears the same name in the province of Lleida. This region is home to different types of geological formations, including the Areniscas de Arén Formation and the Tremp Formation, which have provided a rich and varied yield of dinosaur fossils through the entire Pyrenees region.

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“Eggshells, eggs and nests were found in abundance and they all belong to dinosaurs, sauropods in particular. Up until now, only one type of dinosaur egg had been documented in the region: Megaloolithus siruguei. After analysing more than 25 stratus throughout the Tremp Formation, a minimum of four different additional types were identified: Cairanoolithus roussetensis, Megaloolithus aureliensis, Megaloolithus siruguei and Megaloolithus baghensis,” as explained by Albert García Sellés from the Miquel Crusafont Catalan Palaeontology Institute and lead author of the study.

One of the main problems faced by palaeontologists when studying fossil remains is determining the age of the sediments that contain them. There are fossils known as “guide fossils” whose characteristics allow for the age of rocks to be deduced. However, these fossils are frequent in marine sediments but more scarce and difficult to find in land sediments.

“It has come to light that the different types of eggs (oospecies) are located at very specific time intervals. This allows us to create biochronological scales with a precise dating capacity. In short, thanks to the collection of oospecies found in Coll de Nargó we have been able to determine the age of the site at between 71 and 67 million years,” ensures the expert.

The paleontological sites in the south of Europe containing dinosaur remains have a high scientific value since they allow us to understand and thus reconstruct the ecosystems at the end of the Mesozoic Era.

The latest scientific investigations show that the dinosaur fauna of the European Continent living for a short time before the great extinction some 66 million years ago can be found exactly on the southern side of the Pyrenees.

A connection between French and Spanish dinosaurs

The discovery of Cairanoolithus fossils in this area is an important finding. Given that this type of eggs is only known in the south of France, they are the first of their kind found in the Iberian Peninsula.

According to García Sellés, this discovery constitutes a new proof of the connection between dinosaur fauna in France and in the Iberian Peninsula some 70 million years ago.

Furthermore, finding dinosaur eggs and nests in more than 25 stratigraphic levels provides clear evidence that these sauropods used the Coll de Nargó region as a nesting area for millions of years.

“We had never found so many nests in the one area before. In addition, the presence of various oospecies at the same level suggests that different types of dinosaurs shared the same nesting area,” concludes the scientist.

Secondary Cartilage Revealed in a Non-Avian Dinosaur Embryo

March 12th, 2013 Riffin

The skull and jaws of extant birds possess secondary cartilage, a tissue that arises after bone formation during embryonic development at articulations, ligamentous and muscular insertions. Using histological analysis, we discovered secondary cartilage in a non-avian dinosaur embryo, Hypacrosaurus stebingeri (Ornithischia, Lambeosaurinae). This finding extends our previous report of secondary cartilage in post-hatching specimens of the same dinosaur species. It provides the first information on the ontogeny of avian and dinosaurian secondary cartilages, and further stresses their developmental similarities. Secondary cartilage was found in an embryonic dentary within a tooth socket where it is hypothesized to have arisen due to mechanical stresses generated during tooth formation. Two patterns were discerned: secondary cartilage is more restricted in location in this Hypacrosaurus embryo, than it is in Hypacrosaurus post-hatchlings; secondary cartilage occurs at far more sites in bird embryos and nestlings than in Hypacrosaurus. This suggests an increase in the number of sites of secondary cartilage during the evolution of birds. We hypothesize that secondary cartilage provided advantages in the fine manipulation of food and was selected over other types of tissues/articulations during the evolution of the highly specialized avian beak from the jaws of their dinosaurian ancestors.

Secondary chondrogenesis investigated in hadrosaurid embryos. (A) Reconstruction of the embryonic skull of Hypacrosaurus stebingeri, reproduced with permission [21] with anatomical locations 1, 2 and 3 in green. (B) Transverse section of the surangular of a Hadrosauridae indet. (MOR 1038). (C) Close-up of the red box in (B). The dorso-caudal face (Location 1) does not show any remnant of SC. (D) Coronal section of the maxilla of Hypacrosaurus stebingeri (MOR 559). (E) Close-up of the red box in (D). The bucco-caudal face of the maxilla (Location 2) does not show any remnants of SC. (F) Coronal section of the dentary of Hypacrosaurus stebingeri (MOR 559). (G) Close-up of the red box in (F). The arrow indicates a remnant of dentine. (H) Close-up of the red box in (G). (F) and (G) show alveolar bone (white asterisks) and incomplete alveoli with missing teeth (black asterisk; Location 3). (G) and (H) show a SC islet. All sections are shown under natural light. do, dorsal; la, labial; li, lingual; ro, rostral. doi:10.1371/journal.pone.0056937.g001

Secondary chondrogenesis investigated in hadrosaurid embryos.

Source : Bailleul AM, Hall BK, Horner JR (2013) Secondary Cartilage Revealed in a Non-Avian Dinosaur Embryo. PLoS ONE 8(2): e56937. doi:10.1371/journal.pone.0056937

Editor: Peter Dodson, University of Pennsylvania, United States Of Amerca

 

 

 

 

Species Concepts in Paleontology

March 11th, 2013 Riffin

I.  Various Species Concepts

A.  Determining whether two plants are members of the same species has intriqued and perplexed biologists for a very long time.  Indeed, some question the reality of species from a philosophical standpoint, such as nominalism and realism (see Wikipedia for discussion of this as well as definitions of species).  Darwin said that species did not matter much and basically expressed the idea that they are whatever  a competent taxonomist says they are.  If we follow this idea, you can all go home now – and make sure you become competent when we ask about your species concept! In 1984 Warren H. Wagner Jr. (biography) came up with the following definition of species that helps to set the stage for examining what criteria have been used by scientists to define species.

 

“In light of present usage, I would define species as a convenient taxonomic category that defines a unit of organismic diversity in a given time frame and composed of individual organisms that resemble one another in all or most of their structural and functional characters, that reproduce true by any means, sexual or asexual, and constitute a distinct phylogenetic line that differs consistently and persistently from populations of other species in gaps in character state combinations including geographical, ecological, physiological, morphological, anatomical, cytological, chemical, and genetic, the character states of number and kind ordinarily used for species discrimination in the same and related genera, and if partially or wholly sympatric and coexistent with related species in the same habitats, unable to cross or, if able to cross, able to maintain the special distinctions.”


B.  Biological Species Concept (= genetic species concept, isolation species concept, etc.).

1.  First used by the entomologist Jordan (1896) and later by Mayr (1969) – “a group of interbreeding populations which are reproductively isolated from other groups”.  Mayr later (1982) redefined species as “a reproductive comunity of populations (reproductively isolated from others) that occupies a specific niche in nature.” The genetic species concept aimed to use measured genetic difference (distance) between populations.  Problem with B.S.C. w/ plants:
a.  Gene flow.  Just because there is gene flow does not mean that the plants are not distinct lineages. Numerous examples of hybridization between species exist, but these parental species remain distinct in nature.
b.  Asexual species.  What about apomictic species?  Should each individual be considered a species because it does not interbreed with other individuals?

2.  Reproductive isolation was generally associated with allopatry. The following chart from Mayr illustrates the relationships between these concepts.

 

Individuals Are Not Reproductively   
Isolated       
Reproductively

Isolated
Identical in morphology
and SYMPATRIC		 Same Population Sibling Species
Identical in morphology
and ALLOPATRIC		 Same Subspecies Sibling Species
Different in morphology
and SYMPATRIC		 Variant Individuals
of the same population		 Separate Species
Different in morphology
and ALLOPATRIC
Separate subspecies		 Separate Species

 

C.  Morphological Species Concept.  This is equivalent to the classifical Linnaean concept that uses overt character differences. It is the most common means of circumscribing species (most floras, monographs, etc. use morphological data). Arthur Cronquist (1988, p. 71) said “species are the smallest groups that are consistently and persistently distinct and distinguishable by ordinary means”. But what is considered ordinary means and by whom?  Schull said “ … recognition by any intelligent person with the aid of only a good hand lens”!  But why set an arbitrary limit?


D.  Phenetic Species Concept.  The criteria used to define species involved gaps in character variation.  These ideas were advanced by pheneticists suchas Sokal and Sneath in the 1960s and 70s.  They recognized distinct phenetic clusters obtained following numerical analyses (UPGMA, PCA, etc.).  One problem is determining at what level one should establish as being a species level difference, i.e. where is the phenon line set?

E.  Evolutionary Species Concept.  The criterion was to use common evolutionary fate through time (Wiley 1978).  According to Simpson (1951)  “a lineage evolving separately from others with its own unitary evolutionary role and tendencies”.

F.  Paleontological Species Concept (= Successional, Chronospecies).  This obviously applies to groups with a fossil record, which makes it untenable for many groups without such data.  Also, fossil material presents its own unique set of problems – i.e. incomplete material, inability to conduct crosses, measure gene flow, etc.

G. Phylogenetic Species Concept (= Cladistic or Apomorphic Species Concept).

 

1.  The use of phylogenetic principles, i.e. synapomorphy, shared ancestry, etc. are more applicable to divergent relationships above the level of species. Recall that below this fuzzy line lineages are tokogenetic, i.e. there is gene exchange.  This, and the fact that the term has been used ambiguously, has prompted many systematists to abandoned the use of a phylogenetic  species concept (i.e. see Judd et al. 2008). 2.  The Apomorphy S. C. requires monophyly, i.e. that a species is marked by apomorphies and contains all the descendants of an ancestral population (Donoghue 1985, Mishler 1985).  But as with the Phylogenetic S. C., monophyly is inappropriate below the species level.3.  Typical allopatric speciation by subdivision will generate reciprocally monophyletic daughter species, whereas models such as founder events will produce a paraphyletic parent population and monophyletic daughter population (Rieseberg and Brouillet 1994).  These geographically local modes of speciation (e.g. at the periphery of the distribution of a wide-ranging species) are likely to be more common than transforming the parent species through gene flow or selection.  Thus, is likely that most plant species are paraphyletic.  So again, the criterion of monophyly is not the best way to describe species diversity (Sluys 1991).

4.  Olmstead (1995) proposed using the terms “apospecies” for those that possess a uniquely derived character and “plesiospecies” for those that lack such characters (Figure from his paper).  These are terms that are applied once one has hypotheses of relationships (i.e. trees).  These terms are similar to “cladospecies” and “paraspecies” of Ackery and Vane-Wright (1984).

Phylogenetic species vs. evolutionary species concepts
Phylogenetic species vs. evolutionary species concepts (From John Hawks Weblog)


H.  Diagnosabililty Species Concept.  Proposed by Nixon and Wheeler (1990), it defined a phylogenetic species as “the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of [fixed] character states in comparable individuals.”  But is a small, diagnosable change found in a series of populations (say a single base change on DNA) sufficient to recognize these populations as different species?  Also, how much sampling is required to determine whether any character is truly fixed in a species?

I.  Exclusivity Species Concept (= Geneological, Coalescent).  Proposed by Baum and Shaw (1995), states that members of a group must be “more closely related to one another than to any organisms outside the group”.  Exclusive groups that contain no less inclusive groups are Geneological Species. Exclusivity is determined by gene coalescence, i.e. if the genes of one species can be traced historically to a common ancestor and are more related to each other than to genes of another species. Sets of organisms (populations) for which monophyly cannot be demonstrated are termed “metaspecies”.

II. Plant species – some other topics

A.  Are plant species really different from animals?  Rieseberg et al. (2006) analyzed phenetic and/or crossing data from over 400 genera of plants and animals.  Although discrete phenotypic clusters existed in > 80% of the genera, there was poor (< 60%) correspondence of taxonomic species to these clusters AND this was not different for plants or animals.  75% of phenotypic clusters in plants corresponded to reproductively isolated lineages (postmating isolation).  Plant species turned out to be more likely than animal species to represent reproductively independent lineages.

B. Six paper in Systematic Botany (volume 20 from 1995) were devoted to the species problem in plants.  They were by Davis, Baum and Donoghue, Doyle, Luckow, McDade and Olmstead (see citations below).

References

Ackery, R. R., and R. I. Vane-Wright. 1984. Milkweed butterflies: their cladistics and biology. Cornell University Press, Ithaca, NY.

Baum, D. A., and K. L. Shaw. 1995. Genealogical perspectives on the species problem in P. C. Hoch and A. G. Stephenson, eds. Monographs in Systematic Botany. Missouri Botanical Garden, St. Louis.

Baum, D. A., and M. J. Donoghue. 1995. Choosing among alternative “Phylogenetic” species concepts. Systematic Botany 20: 560-573. JSTOR.

Cronquist, A. 1988. The evolution and classification of flowering plants. New York Botanical Garden, Bronx, New York.

Davis, J. I. 1995. Species concepts and phylogenetic analysis – introduction. Systematic Botany 20: 555-559. JSTOR.

Donohue, M. J. 1985. A critique of the biological species concept and recommendations for a phylogenetic alternative. Bryologist 88: 172-181. JSTOR.

Doyle, J. J. 1995. The irrelevance of allele tree topologies for species delimitation, and a non-topological alternative. Systematic Botany 20: 574-588. JSTOR.

Jordan, K. 1896. On mechanical selection and other problems. Novit. Zool. 3: 426-525.

Luckow, M. 1995. Species concepts: assumptions, methods, and applications. Systematic Botany 20: 589-605. JSTOR.

Mayr, E. 1969. Principles of systematic zoology. McGraw-Hill, New York.

Mayr, E. 1982. The Growth of Biological Thought: Diversity, Evolution and Inheritance. Harvard University Press, Cambridge.

McDade, L. 1995. Species concepts and problems in practice: insight from botanical monographs. Systematic Botany 20: 606-622. JSTOR.

Mishler, B. D. 1985. The morphological, developmental, and phylogenetic basis of species concepts in bryophytes. Bryologist 88: 207-214. JSTOR.

Nixon, K. C., and Q. D. Wheeler. 1990. An amplification of the phylogenetic species concept. Cladistics 6: 211-223.

Olmstead, R. 1995. Species concepts and plesiomorphic species. Systematic Botany 20: 623-630. JSTOR.

Rieseberg, L. H. 1992. The genetic basis of morphological differences between plant species. International Journal of Plant Sciences, 153:5-6. JSTOR.

Rieseberg, L. H., and L. Brouillet. 1994. Are many plant species paraphyletic? Taxon 43: 21-32. JSTOR.

Rieseberg, L. H., T. E. Wood, and E. J. Baack. 2006. The nature of plant species. Nature 440: 524-527. HERE.

Simpson, G. G. 1951. The species concept. Evolution 5: 285-298. JSTOR.

Sluys, R. 1991. Species concepts, process analysis, and the hierarchy of nature. Experientia (Basel) 47: 1162-1170.

Wagner, W. H. 1984. A comparison of taxonomic methods in biosystematics. Pages 643-654 in W. F. Grant, ed. Plant Biosystematics. Academic Press, Toronto.

Wiley, E. O. 1978. The evolutionary species concept reconsidered. Systematic Zoology 24: 17-26. JSTOR.

Source: SIUC / College of Science / Plant Biology / PLB 479 / Lecture PLB479/ Species Concepts

Dinosaurs Died Within Hours After Asteroid Hit Earth 65 Million Years Ago

March 10th, 2013 Riffin

According to earlier research led by a University of Colorado at Boulder geophysicist, a giant asteroid that hit the coast of Mexico 65 million years ago probably incinerated all the large dinosaurs that were alive at the time in only a few hours, and only those organisms already sheltered in burrows or in water were left alive.

photo courtesy: newscenter.lbl.gov

photo courtesy: newscenter.lbl.gov

The six-mile-in-diameter asteroid is thought to have hit Chicxulub in the Yucatan, striking with the energy of 100 million megatons of TNT, said chief author and Researcher Doug Robertson of the department of geological sciences and the Cooperative Institute for Research in Environmental Sciences. The “heat pulse” caused by re-entering ejected matter would have reached around the globe, igniting fires and burning up all terrestrial organisms not sheltered in burrows or in water, he said.

A paper on the subject was published by Robertson in the May-June issue of the Bulletin of the Geological Society of America. Co-authors include CU-Boulder Professor Owen Toon, University of Wyoming Professors Malcolm McKenna and Jason Lillegraven and California Academy of Sciences Researcher Sylvia Hope.

Photo courtesy:amincd.tumblr.com

Photo courtesy:amincd.tumblr.com

“The kinetic energy of the ejected matter would have dissipated as heat in the upper atmosphere during re-entry, enough heat to make the normally blue sky turn red-hot for hours,” said Robertson. Scientists have speculated for more than a decade that the entire surface of the Earth below would have been baked by the equivalent of a global oven set on broil.

The evidence of terrestrial ruin is compelling, said Robertson, noting that tiny spheres of melted rock are found in the Cretaceous-Tertiary, or KT, boundary around the globe. The spheres in the clay are remnants of the rocky masses that were vaporized and ejected into sub-orbital trajectories by the impact.

A nearly worldwide clay layer laced with soot and extra-terrestrial iridium also records the impact and global firestorm that followed the impact.

The spheres, the heat pulse and the soot all have been known for some time, but their implications for survival of organisms on land have not been explained well, said Robertson. Many scientists have been curious about how any animal species such as primitive birds, mammals and amphibians managed to survive the global disaster that killed off all the existing dinosaurs.

Robertson and colleagues have provided a new hypothesis for the differential pattern of survival among land vertebrates at the end of the Cretaceous. They have focused on the question of which groups of vertebrates were likely to have been sheltered underground or underwater at the time of the impact.

Their answer closely matches the observed patterns of survival. Pterosaurs and non-avian dinosaurs had no obvious adaptations for burrowing or swimming and became extinct. In contrast, the vertebrates that could burrow in holes or shelter in water — mammals, birds, crocodilians, snakes, lizards, turtles and amphibians — for the most part survived.

Terrestrial vertebrates that survived also were exposed to the secondary effects of a radically altered, inhospitable environment. “Future studies of early Paleocene events on land may be illuminated by this new view of the KT catastrophe,” said Robertson.

Source: University of Colorado at Boulder article dated May 24, 2004

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