|Evolution in the News - June 2000|
|by Do-While Jones|
|“This is finally evidence for our side,” says paleontologist Jack Horner of the Museum of the Rockies at Montana State University in Bozeman, who has argued that dinosaurs were warm-blooded animals. 8|
Creationists believed that dinosaurs had hearts even before this fossil was found. They will continue to believe it even if the fossil turns out to be a heart-shaped rock. Since dinosaurs could have been created cold-blooded or warm-blooded, their metabolism is of no more importance than their skin color. From a creationist point of view, it would be interesting to know what color they were, whether or not they were warm-blooded, and what sounds they made--but it isn’t vital.
Evolutionists can’t be that impartial. Some are determined to prove dinosaurs were warm-blooded because they feel it strengthens their argument that dinosaurs evolved into birds. Some need to prove dinosaurs were cold-blooded because it strengthens their argument that dinosaurs evolved from reptiles.
Some articles tended to make it seem that the evidence was much more conclusive than it really was. The actual article in Science was much more balanced than most of the reports in the popular press. Science reported the discovery of a well-preserved, nearly intact skeleton. Inside the rib cage, where one would expect to find the animal’s heart, they found heart-shaped rock that is roughly the size that one would calculate that an animal of this size would require. The specimen was imaged in left lateral recumbency with a Picker PQ6000 computerized tomography (CT) scanner, and the image was analyzed on a SUN workstation.
|Patterns of shapes and radiodensities were found to resemble a four-chambered heart. Two adjacent cavities surrounded by iron-rich walls are readily apparent, connected to a dorsally arched tube in a position that is topologically appropriate for a systemic aorta. The thicknesses of the walls delimiting the cavities are consistent with those of ventricles and an interventricular septum, the relative dimensions of which would vary with the degree of distension of the heart at death. The atria are usually very thin-walled compared to the ventricles and often collapse at death, obliterating their internal cavities. They are not reliably discernable in the specimen, nor are the small vessels that are expected in the region of the putative heart base. A radiolucent area immediately adjacent to the systemic aorta, in what would be expected to be lung fields, does not have any surrounding structural detail to suggest that it is associated with the cardiovascular system. 9|
So, they really only saw two chambers, but assume the existence of two more because they probably collapsed. Furthermore, they didn’t see some of the blood vessels one would expect to see. But ABC reported,
Dr. Andrew Kuzmitz, an Ashland, Ore., physician and amateur paleontologist, later examined the specimen with a CT scan, a form of medical X-ray that gives details of internal structure. He said seven cardiologists looked at the images and identified the object as a heart with separated pumping chambers similar to the human heart.
Paul Fisher, director of the NC veterinary school, enhanced the CT scan data into three-dimensional images and the presence of a four-chambered heart became obvious, he said.
“You could see both ventricles [lower heart chambers] and the aorta [a major artery],” said Fisher, the first author of the study.
Fisher said that two more human cardiologists and two veterinarian experts have looked at the images and all agree the chest mass is the fossil of a four-chambered heart. 10
Since there seems to be no disagreement among experts who have actually seen the CT scans, it probably is a fossilized heart. But what does this mean in terms of dinosaur-to-bird evolution. The conclusion of the report was,
|Of the many clades of dinosaurs, in at least one (hypsilophodontids) there is now evidence of an advanced heart with a single systemic aorta. Because of the presence of similar hearts in birds, which are generally considered to be theropod derivatives, it might be concluded that ancestral dinosaurs also possessed an advanced heart (thus making the attribute a synapomorphy for dinosaurs). However, in view of the enormous span of time (>150 million years) separating ancestral dinosaurs from the specimen under consideration, we are uncertain that the effects of long-term parallel selection and evolution on the cardiovascular system were negligible. Whether high metabolic rates and advanced hearts arose once or more than once among dinosaurs remains an open question. 11|
In other words, there are two different branches in the alleged dinosaur family tree. One led to birds, and the other one didn’t. This particular dinosaur is in the other branch. So, they wonder if the supposed “common ancestor” that lived 150 million years earlier than this dinosaur had a four-chambered heart, or if both branches of dinosaurs independently evolved four-chambered hearts.
|Willo [the dinosaur with the heart-shaped fossil] is a Thescelosaurus--one of the so-called bird-hipped dinosaurs. Despite the name, these animals form a separate lineage from the lizard-hipped dinosaurs that may have given rise to birds, says [Dale A.] Russell [a paleontologist at North Carolina State University in Raleigh]. The researchers say the one-aorta heart may have existed in the common ancestor of all dinosaurs or evolved several times in different dinosaur lineages. "I'm putting my money on the double evolution," says Russell. 12|
We’re putting our money on no evolution. Dinosaurs had to have hearts. Whether they looked more like reptile hearts, or bird hearts, or fish hearts is irrelevant. Similarity could just as well be the result of a common designer as a common ancestor.
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Science News, April 22, 2000, page 260
2 ABCNEWS.com, April 23, 2000 (Ev)
3 U.S. News & World Report, May 1, 2000 page 59 (Ev)
4 Time, May 1, 2000, page 62 (Ev)
5 Newsweek, May 1, 2000, page 53 (Ev)
6 Time For Kids, May 8, 2000 (Ev)
7 Fisher, et al. Science, Vol. 288, 21 April, 200, pages 503-505 (Ev)
8 Science News, April 22, 2000, page 260 (Ev)
9 Fisher, et al. Science, Vol. 288, 21 April, 200, page 504 (Ev)
10 ABCNEWS.com, April 23, 2000 (Ev)
11 Fisher, et al. Science, Vol. 288, 21 April 200, page 505 (Ev)
12 Science News, April 22, 2000, page 260 (Ev)