Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans

Body sizes of marine amniotes span six orders of magnitude, yet the factors that governed the evolution of this diversity are largely unknown. High primary production of modern oceans is considered a prerequisite for the emergence of cetacean giants, but that condition cannot explain gigantism in Tr...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) Vol. 374; no. 6575; p. eabf5787
Main Authors: Sander, P Martin, Griebeler, Eva Maria, Klein, Nicole, Juarbe, Jorge Velez, Wintrich, Tanja, Revell, Liam J, Schmitz, Lars
Format: Journal Article
Language:English
Published: United States 24.12.2021
Subjects:
Animals
Aquatic Organisms
Biological Evolution
Body Size
Cetacea - anatomy & histology
Cetacea - physiology
Computer Simulation
Diet
Ecosystem
Food Chain
Fossils
Phylogeny
Reptiles - anatomy & histology
Reptiles - classification
Reptiles - physiology
Skull - anatomy & histology
Vertebrates - anatomy & histology
Vertebrates - physiology
ISSN:1095-9203, 1095-9203
Online Access:Get more information
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Summary:Body sizes of marine amniotes span six orders of magnitude, yet the factors that governed the evolution of this diversity are largely unknown. High primary production of modern oceans is considered a prerequisite for the emergence of cetacean giants, but that condition cannot explain gigantism in Triassic ichthyosaurs. We describe the new giant ichthyosaur sp. nov. with a 2-meter-long skull from the Middle Triassic Fossil Hill Fauna of Nevada, USA, underscoring rapid size evolution despite the absence of many modern primary producers. Surprisingly, the Fossil Hill Fauna rivaled the composition of modern marine mammal faunas in terms of size range, and energy-flux models suggest that Middle Triassic marine food webs were able to support several large-bodied ichthyosaurs at high trophic levels, shortly after ichthyosaur origins.
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ISSN:1095-9203
1095-9203
DOI:10.1126/science.abf5787