Back in 1997, Microsoft's then-CTO, Nathan P. Myhrvold , made headlines when his computer simulations suggested that the enormous tails of sauropods—specifically Apatosaurus —could crack like a bullwhip and break the sound barrier, producing a sonic boom. Paleontologists deemed it an intriguing possibility, although several were skeptical. Now a fresh team of scientists has tackled the issue and built its own simulated model of an Apatosaurus tail. They found no evidence of a sonic boom, according to a new paper published in the journal Scientific Reports. In fact, the maximum speed possible in the new simulations was 10 times slower than the speed of sound in standard air.

While still at Microsoft in the 1990s, Myhrvold—a longtime dinosaur enthusiast—stumbled upon a book by zoologist Robert McNeill Alexander speculating about whether the tails of certain sauropods may have been used like a bullwhip to produce a loud noise as a defensive strategy, a mating call, or other purpose. The structure somewhat resembles a bullwhip, in that each successive vertebra in the tail is roughly 6 percent smaller than its predecessor. It was already well-known in physics circles that the crack of a whip is due to a shock wave, or sonic boom, arising from the speed of the thin tip breaking through the sound barrier.

Myhrvold wanted to put that speculative suggestion to the test, and struck up an email correspondence with paleontologist Philip J. Currie , now at the University of Alberta in Edmonton, Canada. (Fun fact: Currie was one of the inspirations for the Alan Grant character in Jurassic Park .) The two men analyzed fossils, developed computer models, and conducted several computer simulations to test the biomechanics of the sauropod's tail. They also compared those simulations to the mechanics of whips.

Enlarge / A 3D paleoreconstruction of a sauropod dinosaur has revealed that the hind feet had a soft tissue pad beneath the "heel," cushioning the foot to absorb the animals immense weight. (credit: Andreas Jannel)

Ask people to think of a dinosaur, and they'll likely name Tyrannosaurus Rex , the carnivorous antagonist prominently featured in the Jurassic Park and Jurassic World film franchises. But an equally well-known dinosaur clade are the herbivorous sauropods , which include Brachiosaurus, Diplodocus, Apatosaurus , Argentinosaurus , and Brontosaurus . Australian paleontologists have digitally reconstructed these plant-munching giants to glean insight into how their feet managed to support their enormous weight, according to a new paper published in the journal Science Advances.

"We've finally confirmed a long-suspected idea and we provide, for the first time, biomechanical evidence that a soft tissue pad—particularly in their back feet—would have played a crucial role in reducing locomotor pressures and bone stresses," said co-author Andreas Jannel , who worked on the project while completing doctoral studies at the University of Queensland. "It is mind-blowing to imagine that these giant creatures could have been able to support their own weight on land."

Sauropods (clade name: Sauropoda, or "lizard feet") had long-necked, long-tailed bodies that made them the lengthiest animals to have roamed the Earth. They had thick and powerful hind legs, club-like feet with five toes, and more slender forearms. It's rare to find complete Sauropod fossils, and even those that are mostly complete still lack the heads, tail tips, and limbs. Scientists have nonetheless managed to learn a great deal about them, and digital reconstruction is proving to be a valuable new tool in advancing our knowledge even further.

Enlarge / Having this guy stomp through might mean that things would struggle to grow there afterwards. (credit: Roger Harris )

Words I did not expect to read in a scientific paper this week: "The similarity in mass and contact area between modern farm vehicles and sauropods raises the question: What was the mechanical impact of these prehistoric animals on land productivity?" The paper, from Thomas Keller and Dani Or, raises what may be a significant worry: Farm vehicles have grown over the past few decades, to the point where they may be compacting the subsurface soil where roots of crops extend. This poses a risk to agricultural productivity.

The paper then compares that compaction risk to the one posed by the largest animals to ever roam our land: sauropods.

The big crunch

We think of the ground as being solid, but gaps and channels within soil are critical to plant life, since they allow air and water to reach roots. Soil compaction, in its extreme form, gets rid of all these spaces, making the ground much less hospitable for plants. And compaction is hard to reverse; it can take decades of plant and animal activity to break up the compacted soil again and re-establish a healthy ecosystem.