Fish hip bone may connect humans to ocean; Sea monster may rewrite the rules of evolution

Delila James | @@delilalaw| May 14, 2013

Fish hip bone may connect humans to ocean; Sea monster may rewrite the rules of evolution

A busy week in the field of evolutionary theory.

Two major studies seem to be rewriting the rules of evolution.

According to new research on the evolution of the human hip bone, the process of change from the simple hips of a fish to the complex, weight-bearing hips of homo sapiens was far less complicated than previously thought. This study, along with those comparing genetic distances between human and other species, underscores just how closely related all living creatures are to one another.

Four-legged animals, or tetrapods, ventured onto land for the first time about 395 million years ago. One important evolutionary change that made this possible was the development of strong hipbones connected by an ilium. The ilium is the largest, most uppermost bone of the pelvic and is present in birds, mammals, and all reptiles except snakes–but not in fish.


Now, researchers examining the hip structures of the Australian lung fish and the Axoloti, or Mexican Walking Fish, conclude that the transition from basic fish hip to complex human hip could have been accomplished in only a few evolutionary steps.

“Many of the muscles thought to be ‘new’ in tetrapods evolved from muscles already present in lungfish,” said co-author Dr. Catherine Boisvert of the Australian Regenerative Medicine Institute at Monash University.

Boisvert, along with her colleagues Professor Jean Joss of McQuarie University and Professor Per Ahlberg of Sweden’s Uppsala University, discovered that the bones used for sitting would have evolved by the extension of an already present pubis bone and that the connection to the vertebral column could have arisen from an iliac process already existing in fish.

According to Boisvert, the transition from ocean-dwelling to terrestrial animals was a major event in the evolution of land-dwelling creatures, including humans, and the development of a complex, weight-bearing hip bone was an indispensable step.

Studies showing the genetic distance between humans and other species serve to corroborate Boisvert and her colleagues’ findings. For instance, comparative genomics shows that the difference between humans and chimpanzees is a mere 2 percent and that cats and humans share a full 90 percent of their genes. Even the humble fruit fly shares about 60 percent of its genes with human beings–a fact that will seem either fascinating or repugnant, depending one’s point of view.

And while the study is likely to shed light on how human hips came to be, it was just one of two released this week that may end up rewriting the rules of evolution. According to a piece published in National Geographic, researchers have discovered a strange sea monster-like creature that roamed the depths of the ocean tens of millions of year ago. The monster, dubbed Malawania anachronus, was a massive beast, clocking it at over sixty-five feet in length and able to reach speeds of thirty miles per hour. M. anachronus lived 66 million years after the end of the Jurassic period.

The fossil, discovered in the 1950s, however, has researchers scratching their heads. According to scientists, the skeleton seems to resemble a nonexistent lineage never before imagined. According to researchers, the monster seems to resemble its cousins of the Jurassic era, while carbon dating places the creature well into the Cretaceous period. Scientists says it remains unclear why M. anachronus maintained the  same body shape through the millennia, a tactic employed by very few marine creatures. In addition, the lack of skeletal features leaves a number of questions, including why the creature developed a number of specialized features seen in very few other creatures of the time.

Boisvert’s research is published in the journal Evolution and Development.

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