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In a lush ancient landscape, a hungry Triceratops munchies low ferns and cone cycad plants to fuel its 10-ton chassis. The animal swallows huge bites of roughage, seeds and all, before setting off in search of new feeding grounds.
A few days later and miles away, the Triceratops empties its entrails, sowing the seeds of the plants it ate, along with fertilizer, in soil farther away than one could reach without it.
The dispersal of plant seeds throughout animal bodies, known as zoochory, is so common in modern ecosystems that plants often adapt their fruits and flowers to attract specific carriers. Fossils of poop and intestinal contents indicate that plant seeds also harnessed wrinkles in dinosaur bellies, although it is not clear whether these relationships were as widespread and sophisticated as they are today.
George Perry, a forest ecologist at the University of Auckland who studies human pressures on seed dispersal, began to think about this during the coronavirus lockdowns in New Zealand.
“I know from modern ecosystems that large animals are important seed dispersers,” said Dr Perry. “I thought to myself that I had all the parts: what is the most massive animal of all time and how far could it have moved the seeds?”
In a study published Wednesday in Biology Letters, Dr Perry presented a framework for calculating how well dinosaurs – weighing around 20 pounds to 90 tons – could have transported the seeds of prehistoric plants. He found that dinosaurs such as Triceratops or Stegosaurus had the right mix of size and speed to deposit seeds between three and 20 miles from mother plants. This is comparable to the African bush elephant, which carries seeds an average of a mile and a half, but can move them up to 40 miles.
Dr. Perry’s simulations depend on two main factors: the speed of a dinosaur and the length of time it holds seeds before removing them. These values are difficult to pin down due to the limitations of the fossil record. That said, body mass is related to walking speed and seed retention time in modern animals, which can be used as a rough analogue of ecosystems of the past.
“What we really want to be able to do is get a GPS tracker and put it on a dinosaur and track it, but we can’t do that,” Dr Perry said. For this reason, the study’s assumptions are “reasonably conservative,” he added.
Large animals generally travel farther and retain seeds longer than smaller animals. But the extremely massive dinosaurs, such as the 90-ton Argentinosaurus, may have been slower than the medium-sized herbivores. This means that grazers like Triceratops were probably the most efficient seed dispersers due to their smaller body size, but still prodigious appetites.
“The dispersal potentials of the seeds of extinct animals are of great importance, and Dr. Perry estimated those of dinosaurs in a reasonable manner,” said Tetsuro Yoshikawa, a plant ecologist at the National Institute of Studies. environment in Japan which has published research on this topic.
“Since existing land animals, such as elephants and bears, can carry seeds for several miles in some cases, it is possible that large dinosaurs have similar potentials.”
Dr. Perry’s study is “a prime example of how, through intelligent lateral thinking, a scientist can find ways to gain insight into an issue that at first glance could only be answered. with a time machine, ”said John Hall, University of Queensland plant ecologist and cycad plant specialist.
Of course, it would be wonderful if scientists could dip their elbows deep into real dinosaur dung, a la Ellie Sattler in “Jurassic Park.” Sadly, the finer details of these complex ecosystems will likely remain shrouded in mystery and speculation.
“When we look at the natural world today, the diversity and intimacy of the close symbiotic relationships between plants and animals that pollinate flowers and scatter seeds is simply astounding,” said Dr. Hall.
There is “no reason not to think that the specter of these relationships must have been equally complex and diverse in prehistoric times,” he added, even though “these relationships must remain terribly lost for we”.
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