By analyzing data collected from 3,104 fossilized teeth from four different maniraptoran families (small bird-like dinosaurs), researchers from the University of Toronto, the Royal Tyrrell Museum of Palaeontology, and the Royal Ontario Museum believe that early modern birds thrived following the Cretaceous extinction due to their toothless beaks, which were perfect for seed consumption while other food sources dwindled.
The study was recently published in Current Biology.
The fossilized teeth spanned 18 million years, right up until the end-Cretaceous extinction. Across the four maniraptoran families, the teeth maintained their differences, leading the researchers to hypothesize that the ecosystem was rich and stable prior to the catastrophic extinction event.
“There were bird-like dinosaurs with teeth up until the end of the Cretaceous, where they all died off very abruptly,” said study author Derek Larson, of the University of Toronto, in a statement. “Some groups of beaked birds may have been able to survive the extinction event because they were able to eat seeds.”
According to the Smithsonian National Museum of Natural History, the extinction event, which many agree was helped along by an asteroid impact, was likely marked by global forest fires, and cold weather brought on by sun-blocking clouds and dust, which was followed by a period of hot climate due to a rise in carbon dioxide.
“In the fallout of the bolide impact that marks the end of the Cretaceous, terrestrial food webs that relied on photosynthesis would have collapsed,” the researchers wrote. “However seed banks derived from plants, including relatively abundant angiosperms could have been a common, nutrient-rich resource that would have persisted among the detritus.”
According to the researchers, a seed bank can remain viable for more than 50 years in modern temperate forests.
Toothed maniraptorans were likely dependent on food chains that thrived on living plant matter, and were unable to indulge in seed banks.
“Dietary specialization toward granivory in some lineages of crown group birds may have been one of the key factors in their survival through the end-Cretaceous mass extinction,” they wrote.
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