Why dinosaurs ran on two legs, and why most mammals didn’t, according to articles in ScienceDaily and Journal of Theoretical Biology, 2017; 420: 1 DOI: 10.1016/j.jtbi.2017.02.032, published online 27 February 2017.

Palaeontologists Scott Persons and Philip Currie of University of Alberta, Canada, have proposed a theory to explain why many dinosaurs became bipedal, i.e. standing and moving on two legs. According to this theory bipedal dinosaurs inherited this from ancestors known as proto-dinosaurs. Persons explained: “The tails of proto-dinosaurs had big, leg-powering muscles. Having this muscle mass provided the strength and power required for early dinosaurs to stand on and move with their two back feet. We see a similar effect in many modern lizards that rise up and run bipedally”.

The ScienceDaily article goes on to explain: “Over time, proto-dinosaurs evolved to run faster and for longer distances. Adaptations like hind limb elongation allowed ancient dinosaurs to run faster, while smaller forelimbs helped to reduce body weight and improve balance. Eventually, some proto-dinosaurs gave up quadrupedal walking altogether”.

The researchers also claim their theory explains why fast moving mammals have not evolved into bipedal runners. According to Persons and Currie “Bipedal mammals are rare, since burrowing mammal ancestors lost those tail muscles”. Persons explained: “Looking across the fossil record, we can trace when our proto-mammal ancestors actually lost those muscles. It seems to have happened back in the Permian period, over 252 million years ago”. This period is significant in the evolutionary timetable because it is when proto-mammals were evolving early mammals, and they were mainly burrowing animals.


Editorial Comment: Note one simple point: “proto-dinosaurs” with strong tail muscles are now extinct and only known as fossils, as are bipedal dinosaurs, so there actually is no evidence one evolved into the other.

The alterations needed to change an animal with short back legs (that share the load with similar length front legs) into a fully bipedal animal with long strong back legs and short non-load-bearing front legs, will certainly not result from how the animal runs. A major structural change like that requires a change in the growth control genes when the animal is developing as an embryo. A theory that claims that running behaviour resulted in changing four-legged creature into a two-legged creature is reminiscent of the “Just So” stories of Rudyard Kipling, which are children’s fantasy stories, or the theories of Lamarck, which were discredited by the discovery of modern genetics.

Since science deals with present day observations, don’t forget that even though the comparison with living lizards that rise up on their back legs and run is interesting, these observed four legged lizards show no signs of turning into bipedal animals with long weight-bearing hind limbs and short forelimbs. So let’s harp on it! All the real evidence of animals with bipedal structure and function fits with Genesis, i.e. created as fully functional creatures in separate kinds, and reproducing after their kind.

Evidence News, vol. 17, No. 5
29 March 2017
Creation Research Australia

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