Eel-like swimming in the earliest ichthyosaurs

@article{Motani1996EellikeSI,
  title={Eel-like swimming in the earliest ichthyosaurs},
  author={Ryosuke Motani and Y H. and C. Mcgowan},
  journal={Nature},
  year={1996},
  volume={382},
  pages={347-348}
}
ICHTHYOSAURS are extinct marine reptiles, probably belonging to the Diapsida1, that ranged from the Early Triassic to Late Cretaceous2,3. Post-Triassic ichthyosaurs achieved the highest level of aquatic adaptation among reptiles4, with a streamlined body, lunate tail and a dorsal fin, features exemplified today by thunniform (tuna-like) fishes. However, little is known of how such a body plan evolved from a terrestrial diapsid. Here we report the most complete specimen of the oldest known… 

Osteohistology of the Early Triassic Ichthyopterygian Reptile Utatsusaurus hataii: Implications for Early Ichthyosaur Biology

TLDR
The first osteohistological data concerning the most basal ichthyopterygian yet known, Utatsusaurus hataii, from the Lower Triassic of Japan is presented, and the cancellous bone structure suggests adaptation to active swimming in an open marine environment.

Ichthyosaurian relationships illuminated by new primitive skeletons from Japan

TLDR
Phylogenetic analyses indicate that ichthyosaurs belong in the Diapsida, but that, unlike the sauropterygians, they are not included with the Sauria (the crown group containing lizards, crocodiles, birds and Sphenodon).

New findings reveal that the middle Triassic ichthyosaur Mixosaurus cornalianus is the oldest amniote with a dorsal fin.

Two excellently preserved specimens of Mixosaurus cornalianus from the Anisian layers of the Middle Triassic Formazione di Besano, with soft parts associated with well-articulated skeletal elements,

ADRIOSAURUS AND THE AFFINITIES OF MOSASAURS, DOLICHOSAURS, AND SNAKES

TLDR
Phylogenetic analysis of 258 osteological characters and all the major squamate lineages suggests that Adriosaurus and dolichosaurs are successive sister-taxa to snakes, refuting recent suggestions that snakes cluster with amphisbaenians and dibamids (rather than aquatic lizards) if multistate characters are left unordered.

Landlubbers to leviathans: evolution of swimming in mosasaurine mosasaurs

Abstract Incremental stages of major evolutionary transitions within a single animal lineage are rarely observed in the fossil record. However, the extraordinarily complete sequence of well preserved

A longirostrine Temnodontosaurus (Ichthyosauria) with comments on Early Jurassic ichthyosaur niche partitioning and disparity

TLDR
The question of whether postcrisis recovery of vertebrate faunas, including the radiation of Temnodontosaurus into a new ecological niche, may have been a consequence of marine ecosystem reorganization across this event is raised.

Evolution of Fish-Shaped Reptiles (reptilia: Ichthyopterygia) in Their Physical Environments and Constraints

TLDR
Ichthyosaurs were a group of Mesozoic marine reptiles that evolved fish-shaped body outlines that allowed estimation of such characteristics as optimal cruising speed, visual sensitivity, and even possible basal metabolic rate ranges.

Soft tissue preservation in a fossil marine lizard with a bilobed tail fin.

TLDR
This fossil is reported from the Maastrichtian of Harrana in central Jordan, which preserves soft tissues, including high fidelity outlines of a caudal fluke and flippers, which provides the first indisputable evidence that derived mosasaurs were propelled by hypocercal tail fins.

The Evolution of Marine Reptiles

  • R. Motani
  • Environmental Science, Geography
    Evolution: Education and Outreach
  • 2009
TLDR
There were more than a dozen groups of marine reptiles in the Mesozoic, of which four had more than 30 genera, namely sauropterygians (including plesiosaurs), ichthyopterygian, mosasaurs, and sea turtles, who explored many different swimming styles and diets.

Middle–Upper Triassic marine vertebrates of Mallorca (Balearic Islands, western Mediterranean)

TLDR
An anterior caudal vertebra of a basal ichthyosauriform similar to Grippidia is described from the Ladinian carbonate ramps of the Muschelkalk of Mallorca, which fills a biogeographic gap for the group, hitherto only known from the eastern and western margins of Panthalassa.
...

References

SHOWING 1-9 OF 9 REFERENCES

The affinities and ecology of Triassic ichthyosaurs

The resolution of the problem of ichthyosaurian affinities has been complicated and prolonged by an emphasis on the morphology of Jurassic ichthyosaurs, some 30 to 40 m.y. younger than the earliest

Swimming capabilities of Mesozoic marine reptiles: implications for method of predation

TLDR
Estimating the total drag and the amount of energy available through metabolism, the maximum sustained swimming speed was calculated for 115 marine reptile specimens and suggests that the long-bodied forms probably used an ambush technique to capture prey, to maximize the range of possible prey and to minimize competition with the faster pursuit predators.

Body Form and Locomotion in Sharks

TLDR
The locomotor mechanism of sharks is adapted for an efficient cruising swimming but at the same time, the potential instability in the sagittal plan allows for the production of turning moments that are used in attack and feeding.

Simple Physical Principles and Vertebrate Aquatic Locomotion

TLDR
Numerical solutions to models estimate thrust and drag, and rates of working, which are several times greater than expected for manmade non-flexing bodies, used in prediction of optimal two-phase swimming behaviors.

Biology of the Reptilia

  • C. Gans
  • Biology, Environmental Science
  • 1969
Why Study Reptilian Development? The Origin and Development of Oocytes Embryology of Turtles Embryology of Marine Turtles Development of Crocodilians Embryology of the Tuatara Some Developmental

Sharks and Rays of Australia

TLDR
An essential tool for conservation biologists trying to save threatened sharks, now under siege worldwide, this marvelous volume will also appeal to fish biologists, divers, naturalists, commercial and recreational fishermen, and anyone with an appreciation for these ancient evolutionary survivors.