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New investigation suggests that nan earliest dinosaurs whitethorn person originated successful equatorial regions of Gondwana, encompassing nan Amazon, Congo Basin, and nan Sahara Desert. Fossils making love backmost 230 cardinal years, recovered successful areas for illustration Brazil and Argentina, bespeak dinosaurs had evolved earlier, but fossil gaps complicate nan record.
A caller study led by researchers from University College London (UCL) suggests that nan earliest dinosaur remains whitethorn still beryllium hidden successful nan Amazon and different equatorial regions of South America and Africa.
The oldest known dinosaur fossils, making love backmost astir 230 cardinal years, person been discovered successful confederate locations specified arsenic Brazil, Argentina, and Zimbabwe. However, differences among these fossils bespeak that dinosaurs had already been evolving for immoderate time, suggesting their origins whitethorn predate these finds by millions of years.
Published successful nan diary Current Biology, nan study analyzed gaps successful nan fossil grounds and concluded that nan first dinosaurs apt emerged successful a hot, equatorial region wrong nan ancient supercontinent Gondwana. This area corresponds to modern-day regions including nan Amazon, nan Congo Basin, and nan Sahara Desert.
Fossils Yet to Be Found
Lead writer and PhD student Joel Heath (UCL Earth Sciences and nan Natural History Museum, London) said: “Dinosaurs are good studied but we still don’t really cognize wherever they came from. The fossil grounds has specified ample gaps that it can’t beryllium taken astatine look value.
“Our modeling suggests that nan earliest dinosaurs mightiness person originated successful western, low-latitude Gondwana. This is simply a hotter and drier situation than antecedently thought, made up of desert- and savannah-like areas.
“So far, nary dinosaur fossils person been recovered successful nan regions of Africa and South America that erstwhile formed this portion of Gondwana. However, this mightiness beryllium because researchers haven’t stumbled crossed nan correct rocks yet, owed to a operation of inaccessibility and a comparative deficiency of investigation efforts successful these areas.”
The modeling study drew connected fossils and evolutionary trees of dinosaurs and their adjacent reptile relatives, arsenic good arsenic nan surface science of nan period. It accounted for gaps successful nan fossil grounds by treating areas of nan globe wherever nary fossils had been recovered arsenic missing accusation alternatively than areas wherever nary fossils exist.
Initially, early dinosaurs were vastly outnumbered by their reptile cousins.
These included nan ancestors of crocodiles, nan pseudosuchians (an abundant group including tremendous species up to 10 meters long), and pterosaurs, nan first animals to germinate powered formation (flying by flapping wings alternatively than gliding), who grew arsenic large arsenic combatant jets.
By contrast, nan earliest dinosaurs were overmuch smaller than their descendants – much nan size of a chickenhearted aliases canine than a Diplodocus. They walked connected 2 legs (were bipedal) and astir are thought to person been omnivores.
Dinosaurs became ascendant aft volcanic eruptions wiped retired galore of their reptile relatives 201 cardinal years ago.
Expansion and Adaptation of Dinosaurs
The caller modeling results suggested that dinosaurs arsenic good arsenic different reptiles whitethorn person originated successful low-latitude Gondwana, earlier radiating outwards, spreading to confederate Gondwana and to Laurasia, nan adjacent bluish supercontinent that later divided into Europe, Asia, and North America.
Support for this root comes from nan truth it is simply a midpoint betwixt wherever nan earliest dinosaurs person been recovered successful confederate Gondwana and wherever nan fossils of galore of their adjacent relatives person been discovered to nan northbound successful Laurasia.
As location is uncertainty astir really nan astir ancient dinosaurs were related to 1 different and to their adjacent relatives, nan researchers ran their exemplary connected 3 projected evolutionary trees.
They recovered nan strongest support for a low-latitude Gondwanan root of nan dinosaurs successful nan exemplary that counted silesaurids, traditionally regarded arsenic cousins of dinosaurs but not dinosaurs themselves, arsenic ancestors of ornithischian dinosaurs.
Ornithischians, 1 of nan 3 main dinosaur groups that later included works eaters Stegosaurus and Triceratops, are mysteriously absent from nan fossil grounds of these early years of nan dinosaur era. If silesaurids are nan ancestors of ornithischians, this helps to capable successful this spread successful nan evolutionary tree.
Climate and Dinosaur Evolution
Senior writer Professor Philip Mannion (UCL Earth Sciences) said: “Our results propose early dinosaurs whitethorn person been good adapted to basking and arid environments. Out of nan 3 main dinosaur groups, 1 group, sauropods, which includes nan Brontosaurus and nan Diplodocus, seemed to clasp their penchant for a lukewarm climate, keeping to Earth’s little latitudes.
“Evidence suggests nan different 2 groups, theropods, and ornithischians, whitethorn person developed nan expertise to make their ain assemblage power immoderate millions of years later successful nan Jurassic period, allowing them to thrive successful colder regions, including nan poles.”
The earliest known dinosaurs see Eoraptor, Herrerasaurus, Coelophysis, and Eodromaeus.
Reference: “Accounting for sampling heterogeneity suggests a debased paleolatitude root for dinosaurs” by Joel A. Heath, Natalie Cooper, Paul Upchurch and Philip D. Mannion, 23 January 2025, Current Biology.
DOI: 10.1016/j.cub.2024.12.053