The rapid expansion of DNA testing capability and general efficiencyis now so mature that we are actually mopping up some of the bigobvious tasks. I have no doubt that this will soon be expanded tobirds in particular and all land animals out there.
We continue to confirm that the mammal did not become a factor at alluntil post K-T. I am not so sure that that will hold up simplybecause egg eating works so well for rats in particular. That andinsect eating and we can anticipate a very successful mammal and manysmall successful reptiles who are out there.
What the K-T provided was a newly reborn biome with ample scope forlarger creatures which was then filled fastest by the mammals incompetition with the birds who also went to giantism.
Now the task of sorting out and correcting our morphological data iswell begun also.
Largest-ever studyof mammalian ancestry completed by renowned research team
by Staff Writers
Pittsburgh PA(SPX) Feb 11, 2013
This is anartist's rendering of the hypothetical placental ancestor, a smallinsect-eating animal. The research team reconstructed the anatomy ofthe animal by mapping traits onto the evolutionary tree most stronglysupported by the combined phenomic and genomic data and comparing thefeatures in placental mammals with those seen in their closestrelatives. Credit: Carl Buell.
http://www.terradaily.com/reports/Largest_ever_study_of_mammalian_ancestry_completed_by_renowned_research_te_999.html
A groundbreakingsix-year research collaboration has produced the most completepicture yet of the evolution of placental mammals, the group thatincludes humans.
Placental mammals arethe largest branch of the mammalian family tree, with more than 5,100living species. Researchers from Carnegie Museum of Natural Historyare among the team of 23 that took part in this extensiveinterdisciplinary effort that utilizes molecular (DNA) andmorphological (anatomy) data on an extraordinary scale.
By combining these twotypes of data scientists reconstructed, to an unprecedented level ofdetail, the family tree of placental mammals. This study exploredthousands of characteristics of the anatomy of both living andextinct placental mammals.
This new projectproduced a more complete picture of mammalian history and provides ahuge dataset that will become the starting point of research for anumber of scientific questions, including those of vital importancetoday: how mammals may have survived climate change in the past andwhat may that mean for our future. The paper appears today in thejournal Science.
The collaboration ispart of the Assembling the Tree of Life (ATOL) project funded by theNational Science Foundation.
Joining forces,joining research
Today's articlereveals the final results of the six-year ATOL project. The studybegan with two teams organizing data from two distinct approaches toevolutionary research: molecular data (DNA), and morphological data(anatomical features).
"In the field ofmammal research, there had been a big divide between people workingwith DNA and others working on morphology," explains John Wible,PhD, Curator of Mammals at Carnegie Museum of Natural History andco-author on the paper. "They just weren't working with eachother until now."The molecular teamcollected DNA sequences of living animals and the morphology teamexamined the anatomy of both living and extinct mammals. Themolecular team only sampled living mammals, because genetic materialcan't be extracted from fossils older than 30,000 years,. Thus, toinclude fossils, morphological information was essential. Researchersin morphology deal with individual physical features, from bonelength to types of teeth to the presence of stripes in the fur; eachone of these features is termed a 'character.' By collecting as manycharacters as possible and comparing their variation among dozens ofspecimens, relationships between species can be tested and broaderpatterns emerge.
The ATOL projectbecame a morphological powerhouse. Generally, a group of 500characters is considered to be a large dataset. The morphologyresearchers on the ATOL project generated an unprecedented 4,500characters. Once both DNA and morphological datasets were produced,the resulting combined matrix provided an unprecedented amount ofinformation for each of the 83 mammals included in the study.
"It's not that wehadn't combined morphology with DNA before." clarifies co-authorMichelle Spaulding, PhD, the Rea Post-doctoral Fellow at CarnegieMuseum of Natural History. "This time, we ratcheted up theamount of morphological detail phenomenally, providing a largeranatomical base for the study as compared with DNA than is typical.."
With the new Tree ofLife matrix, researchers now have greater context for the fragmentaryfossils they have in hand-often scant evidence such as a few teeth ora skull fragment-potentially shedding light on little-known speciesthat have yet to find a solid home in the evolutionary tree.
Ancestral originsestimated
Thanks to theincredible amount of anatomical information collected, theresearchers were able to predict the appearance of the most recentcommon ancestor of all placental mammals. Explains Spaulding, "Wehave all these placentals alive today, from elephants to shrews, fromthings that fly to things that swim. What could the common ancestorof these things that are so different possibly look like?"
"That's the powerof 4,500 characters," says Wible. "We looked at all aspectsof mammalian anatomy, from the skull and skeleton, to the teeth, tointernal organs, to muscles, and even fur patterns. Using the newfamily tree of mammals in tandem with this anatomical data, we wereable to reconstruct what this common placental ancestor may havelooked like."
The scientists wereable to work with an artist to approximate the appearance of thisancestor. While only hypothetical, the illustrated concept for thisancestor-from body size to fur type to number of teeth-could not havebeen achieved prior to the Herculean task of developing the matrix.
Earliest date forplacentals
"We focusedour study on the time around the Cretaceous-Tertiary (KT) boundary,65 million years ago," states Spaulding, "Molecular andmorphological based studies differ on the age when placentals firstappeared. Molecular studies place the origin in the mid-Cretaceous,when dinosaurs still dominated. On the other hand, morphologicalstudies have routinely found no evidence of any placental fossils inthis time period, and instead place the placental origin after themass extinction at the close of the Cretaceous that ended dinosaurdominance."
One major goal of thisproject was to address this controversy and results found thatplacental mammals appeared after the KT boundary, implying that themass extinction was a critical event in mammalian evolutionaryhistory.
New website anessential tool
The study wasconducted utilizing the web application Morphobank(www.morphobank.org). The matrix is freely available online andprovides a road map to the Tree of Life team's findings by preciselyoutlining how the team defined each of the more than 4,500 charactersin the dataset. Proving that a picture is worth a thousand words, themajority of characters include illustrations.As revolutionary asthe study, the website also marks a new era in how collaborativeresearch may proceed. "We couldn't have accomplished thiswithout Morphobank," lauds Spaulding. "This website allowedmembers of the team, spread all over the globe, to worksimultaneously."
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