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ScienceNOW: “Placental Mammals Climb a New Tree”
We’re not as old as we thought—or so paleontologist John Wible of the Carnegie Museum of Natural History and colleagues have concluded about the origin of mammals. Opposing the date of 140–80 million years old that some scientists ascribe to our (supposed) oldest mammalian ancestors, Wible, et al., conclude, based on an analysis of a shrewlike fossil, that mammals evolved “only” 65 million years ago. A ScienceNOW article elaborates:
In 1997, the team unearthed the jaw and parts of the backbone, ribs, skull, and limbs of a shrewlike species, which they named Maelestes gobiensis. By comparing 400 morphological features [...] in the new fossil with those in 68 other specimens, the researchers have now placed the 73-million-year-old creature in the Eutherian evolutionary tree, an umbrella group that includes placental mammals.
But the new data have forced the team to redraw the tree. According to the new tree, the first placental mammals appeared around 65 million years ago, not 100 million years ago or more, as some molecular data have suggested. What's more, the new tree indicates that these mammals very quickly diversified into the modern groups, close to the downfall of the dinosaurs[.]
Notice that dates such as these are rigid and non-negotiable, “proven by science” when brought up in a debate over evolution and creation, but evolutionary scientists conveniently ignore these dates when they fly in the face of their research.
While purportedly refining the mammalian branch of the tree of life, the study has actually exposed one of the problems underlying old-age paleontological extrapolations into the history of life on earth. The article casually notes that “DNA evidence places the first placental mammals anywhere from 140 million to 80 million years ago,” even though Wible’s team’s conclusions flatly contradict this window. Notice that dates such as these are rigid and non-negotiable, “proven by science” when brought up in a debate over evolution and creation, but evolutionary scientists conveniently ignore these dates when they fly in the face of their research.
But Stephen O’Brien, an evolutionary biologist with the National Cancer Institute, “criticizes Wible and colleagues for not factoring in the genetic evidence”:
“I think their data are okay, but their global interpretation and hypotheses are anything but supported [by the data],” he says.
So when the evolutionary “evidence”—genetic and fossil evidence, in this case—fail to mesh and instead leave a 15-million-year (minimum!) contradiction, do any scientists admit that they may be wrong? Are the genetic dating method or the paleontological dating methods criticized or questioned? We’ll let Wible explain his reaction to the contradiction:
Both molecular and fossil studies have their shortcomings, says Wible, but by analyzing lots of characters in lots of species, he is convinced his tree is trustworthy.
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