One of the traits that helped make the dinosaurs such an evolutionary success story — thriving for 165 million years — was their fast growth rate, from massive meat-eaters like Tyrannosaurus to immense plant-eaters like Argentinosaurus.
But when did this characteristic first appear? A new study indicates it was present in the earliest dinosaurs, as revealed by microscopic features in bone fossils from Argentina that showed that they exhibited growth rates on par with those of today’s mammals and birds.
ADVANTAGES OF RAPID GROWTH
Photo: Sergei Krasinski via Reuters
“Growing quickly allows organisms to escape the risky business of being small for a long part of their life history. It also allows them more time to reproduce throughout their lifespan, which imparts a measure of evolutionary fitness, generation by generation,” said paleontologist Kristi Curry Rogers of Macalester College in Minnesota, lead author of the study published this month in the journal PLOS ONE.
The researchers examined patterns preserved within the bones of dinosaurs and some of their cousins that inhabited northwestern Argentina between about 231 and 229 million years ago.
“The organization of minute bone mineral crystals and proteins, along with blood vessels and cellular organization, all reflect relative speed of growth,” Curry Rogers said. “Of course, all these soft squishy parts have long since decayed, millions of years ago, when these bones were becoming fossils. But all the hard parts that persist through time record the spaces where these soft parts once were. This allows us to reconstruct and compare growth patterns among animals.”
Photo: Reuters
The researchers studied five early dinosaurs — all bipedal, fleet-footed and with clawed, grasping hands and sharp teeth.
Three were meat-eaters, forerunners of massive predators such as T rex and Giganotosaurus. Herrerasaurus and Sanjuansaurus were around 13-4.5 meters long, while Eodromaeus was about the size of a turkey.
The other two — similarly turkey-sized Eoraptor and Chromogisaurus — were forerunners of long-necked, four-legged giants such as Argentinosaurus and Dreadnoughtus.
Photo: Reuters
All five showed signs of exceptionally fast growth.
RULING REPTILES
But the researchers also got a bit of a surprise when they discovered that some of the non-dinosaur reptiles in these ancient Argentine ecosystems were keeping pace, having their own speedy growth rates.
“Dinosaurs arose from humble origins, starting off as small, bipedal carnivores, who were themselves dominated by a diverse array of other ruling reptiles,” Curry Rogers said.
Quick growth was detected in fearsome four-legged crocodile-like Saurosuchus, the dominant terrestrial predator of its time at about 7 meters long, as well as crocodile relatives Proterochampsa and Trialestes.
Other animals including tusked plant-eating reptile Hyperodapedon and mammal-like reptile Exaeretodon also grew quickly, but regularly paused their growth throughout life — a pattern distinctive from the continuous fast growth of dinosaurs.
The first dinosaurs and these other animals evolved during the Triassic Period. This was in the aftermath of Earth’s worst mass extinction 252 million years ago at the end of the Permian Period. About 95 percent of species were lost amid severe climate change apparently caused by massive Siberian volcanic activity.
“Since these dinosaurs shared their fast growth rates with a number of other animals that are distant relatives, it seems that growing fast was good for everyone in a turbulent world,” Curry Rogers said. “Fast growth, combined with so many other unique aspects of dinosaur physiology, biology and behavior likely gave dinosaurs a leg up. But it was this unique combination — not the single feature of growing up quickly — that gave dinosaurs their evolutionary jump start.”
Another mass extinction at the end of the Triassic about 201 million years ago doomed many of the early competitors to the dinosaurs, allowing the dinosaurs to assert true dominance.
“As time would continue to unroll, the dinosaurs would hold onto these elevated growth rates, while their non-dinosaur compatriots would slow things down,” Curry Rogers said. “These changes accompany major shifts in diversity through this time. As dinosaurs become more disparate, their crocodile-cousins get canalized into a much narrower range of growth patterns and lifestyle.”
That US assistance was a model for Taiwan’s spectacular development success was early recognized by policymakers and analysts. In a report to the US Congress for the fiscal year 1962, former President John F. Kennedy noted Taiwan’s “rapid economic growth,” was “producing a substantial net gain in living.” Kennedy had a stake in Taiwan’s achievements and the US’ official development assistance (ODA) in general: In September 1961, his entreaty to make the 1960s a “decade of development,” and an accompanying proposal for dedicated legislation to this end, had been formalized by congressional passage of the Foreign Assistance Act. Two
Despite the intense sunshine, we were hardly breaking a sweat as we cruised along the flat, dedicated bike lane, well protected from the heat by a canopy of trees. The electric assist on the bikes likely made a difference, too. Far removed from the bustle and noise of the Taichung traffic, we admired the serene rural scenery, making our way over rivers, alongside rice paddies and through pear orchards. Our route for the day covered two bike paths that connect in Fengyuan District (豐原) and are best done together. The Hou-Feng Bike Path (后豐鐵馬道) runs southward from Houli District (后里) while the
March 31 to April 6 On May 13, 1950, National Taiwan University Hospital otolaryngologist Su You-peng (蘇友鵬) was summoned to the director’s office. He thought someone had complained about him practicing the violin at night, but when he entered the room, he knew something was terribly wrong. He saw several burly men who appeared to be government secret agents, and three other resident doctors: internist Hsu Chiang (許強), dermatologist Hu Pao-chen (胡寶珍) and ophthalmologist Hu Hsin-lin (胡鑫麟). They were handcuffed, herded onto two jeeps and taken to the Secrecy Bureau (保密局) for questioning. Su was still in his doctor’s robes at
Mirror mirror on the wall, what’s the fairest Disney live-action remake of them all? Wait, mirror. Hold on a second. Maybe choosing from the likes of Alice in Wonderland (2010), Mulan (2020) and The Lion King (2019) isn’t such a good idea. Mirror, on second thought, what’s on Netflix? Even the most devoted fans would have to acknowledge that these have not been the most illustrious illustrations of Disney magic. At their best (Pete’s Dragon? Cinderella?) they breathe life into old classics that could use a little updating. At their worst, well, blue Will Smith. Given the rapacious rate of remakes in modern
RSS