Dinosaur vision

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Dinosaur vision was, in general, better than the vision of most other reptiles, although vision varied between dinosaur species. Coelurosaurs, for example, had good stereoscopic or binocular vision, whereas large carnosaurs had poor binocular vision, comparable to that of modern alligators. Recent evidence has also shown that some species possessed highly specialized color and night vision. [1] [2]

Contents

Theropoda

Allosauroidea

Allosauroids, including Carcharodontosaurus [3] and Allosaurus , did not have very good binocular vision, comparable to modern crocodiles. [4] They possessed binocular vision which was restricted to a region only 20° wide, which is understandable, as they hunted mostly large and slow prey. Their keenest sense was probably smell.

Deinonychosauria

The binocular vision of deinonychosaurs, such as Velociraptor and Stenonychosaurus was better than that of allosauroids and it matched or exceeded that of extant predatory birds. Their binocular field was up to 60°. [4]

Tyrannosauridae

The position of the eyes of tyrannosaurids suggests that they had a very well developed sense of vision. Combined with the shape of the head they had better binocular vision than allosauroids. The eye position of Tyrannosaurus rex was similar to that of modern humans, but their eyes and optic lobe were much larger than that of modern humans. T. rex, unlike most dinosaurs, had a combination of powerful eyesight and a great sense of smell. The binocular vision of Daspletosaurus has been found to be less than that of Stenonychosaurus, but more than that of Gorgosaurus . [4]

Ceratosauria

Ceratosaurs had eyes placed closer to the side. This widened their field of vision, but decreased their depth perception.[ citation needed ]

Ornithischia

Pachycephalosauria

Pachycephalosaurs, like most of the plant-eaters, had eyes on the sides of the head, so they could quickly spot approaching predators. They also had better depth perception than most other dinosaurs [ citation needed ]

Night Vision

This area of research has focused on whether certain species of dinosaur possessed acute night vision, or if such nocturnal adaptations were exclusive to smaller mammals and later, birds. [5] Computerized Tomography has revealed evidence suggesting that several dinosaur species possessed formidable night vision and were capable of extensive nocturnal activity. [5]

The scleral ring is critical in determining a dinosaur's nocturnal capacity. Diameter and circumference of the structure directly correlate with the effectiveness of modern animal night vision and is hypothesized to do the same in dinosaurs. [2] A larger scleral ring indicates an increased capacity to capture ambient light, thereby amplifying nocturnal visual acuity. [2]

Small herbivores, such as the Shuvuuia deserti, were found to have particularly large scleral ring's. [6] Taken in tandem with previous findings of extremely sensitive hearing, researchers concluded that they likely possessed acute night vision for nocturnal activity. [2] Large carnivorous theropods, such as the Tyrannosaurus and Dromaeosaurus , were found to have much smaller scleral rings and likely had visual capacities more suited to daytime activity. [2]

Color Vision

Dinosaur color vision is studied by evaluating fossil records and reconstructing biomes; researchers can make inferences about the biological structures that are needed to interact with a dinosaurs hypothesized environment. [7]

Melanosomes have been identified in the fossilized feathers of certain dinosaur species. The presence of melanosomes in bird feathers indicates the potential for enhanced color discrimination. [1] Modern birds whose feathers contain melanosome-like structures are tetrachromats. [1] Tetrachromacy refers to the possession of four types of cone cells in the eyes, allowing for enhanced color vision. [8]

Because melanosomes are associated with enhanced color vision in birds today, the presence of these structures in early dinosaurs suggests that they may have also been tetrachromats. [1] This hypothesis implies that these dinosaurs had advanced color vision, potentially aiding them in tasks such as finding food, identifying mates, and communicating with conspecifics. [1] Specifically, these tetrachromats are capable of discriminating shades of turquoise and ultraviolet that trichromats, like humans, cannot. [8]

Related Research Articles

<span class="mw-page-title-main">Dinosaur</span> Archosaurian reptiles that dominated the Mesozoic Era

Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds.

<span class="mw-page-title-main">Theropoda</span> Clade of dinosaurs

Theropoda, whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores and omnivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago (Ma) and included the majority of large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species.

<i>Stenonychosaurus</i> Theropod dinosaur

Stenonychosaurus is a genus of troodontid dinosaur from the Late Cretaceous Dinosaur Park Formation of Alberta, Canada, as well as possibly the Two Medicine Formation. The type and only species, S. inequalis, was named by Charles Mortram Sternberg in 1932, based on a foot, fragments of a hand, and some caudal vertebrae from the Late Cretaceous of Alberta. S. inequalis was reassigned in 1987 by Phil Currie to the genus Troodon, which was reverted by the recognition of Stenonychosaurus as a separate genus from the possibly dubious Troodon in 2017 by Evans et al. and also later in the same year by Van der Reest and Currie.

<i>Sinosauropteryx</i> Extinct genus of dinosaurs

Sinosauropteryx is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae to be found with evidence of feathers. It was covered with a coat of very simple filament-like feathers. Structures that indicate colouration have also been preserved in some of its feathers, which makes Sinosauropteryx the first non-avialian dinosaurs where colouration has been determined. The colouration includes a reddish and light banded tail. Some contention has arisen with an alternative interpretation of the filamentous impression as remains of collagen fibres, but this has not been widely accepted.

<i>Shuvuuia</i> Extinct family of bird-like dinosaurs

Shuvuuia is a genus of bird-like theropod dinosaur from the late Cretaceous period of Mongolia. It is a member of the family Alvarezsauridae, small coelurosaurian dinosaurs which are characterized by short but powerful forelimbs specialized for digging. The type species is Shuvuuia deserti, or "desert bird". The name Shuvuuia is derived from the Mongolian word shuvuu (шувуу) meaning "bird".

<i>Microraptor</i> Extinct genus of dinosaurs

Microraptor is a genus of small, four-winged dromaeosaurid dinosaurs. Numerous well-preserved fossil specimens have been recovered from Liaoning, China. They date from the early Cretaceous Jiufotang Formation, 125 to 120 million years ago. Three species have been named, though further study has suggested that all of them represent variation in a single species, which is properly called M. zhaoianus. Cryptovolans, initially described as another four-winged dinosaur, is usually considered to be a synonym of Microraptor.

<i>Carcharodontosaurus</i> Genus of carcharodontosaurid dinosaur from the Cretaceous period

Carcharodontosaurus is a genus of carnivorous theropod dinosaur that lived in North Africa from about 100 to 94 million years ago during the Cenomanian stage of the Late Cretaceous. Two teeth of the genus, now lost, were first described from Algeria by French paleontologists Charles Depéret and Justin Savornin as Megalosaurus saharicus. A partial skeleton was collected by crews of German paleontologist Ernst Stromer during a 1914 expedition to Egypt. Stromer did not report the Egyptian find until 1931, in which he dubbed the novel genus Carcharodontosaurus, making the type species C. saharicus. Unfortunately, this skeleton was destroyed during the Second World War. In 1995 a nearly complete skull of C. saharicus, the first well-preserved specimen to be found in almost a century, was discovered in the Kem Kem Beds of Morocco; it was designated the neotype in 1996. Fossils unearthed from the Echkar Formation of northern Niger were described and named as another species, C. iguidensis, in 2007.

<i>Beipiaosaurus</i> Extinct genus of dinosaurs

Beipiaosaurus is a genus of therizinosauroid theropod dinosaurs that lived in China during the Early Cretaceous in the Yixian Formation. The first remains were found in 1996 and formally described in 1999. Before the discovery of Yutyrannus, Beipiaosaurus were among the heaviest dinosaurs known from direct evidence to be feathered. Beipiaosaurus is known from three reported specimens. Numerous impressions of feather structures were preserved that allowed researchers to determine the feathering color which turned out to be brownish.

<span class="mw-page-title-main">Feathered dinosaur</span> Dinosaur with feathers

A feathered dinosaur is any species of dinosaur possessing feathers. That includes all species of birds, and in recent decades evidence has accumulated that many non-avian dinosaur species also possessed feathers in some shape or form. The extent to which feathers or feather-like structures were present in dinosaurs as a whole is a subject of ongoing debate and research.

<i>Sinornithosaurus</i> Extinct genus of dinosaurs

Sinornithosaurus is a genus of feathered dromaeosaurid dinosaur from the early Cretaceous Period of the Yixian Formation in what is now China. It was the fifth non–avian feathered dinosaur genus discovered by 1999. The original specimen was collected from the Sihetun locality of western Liaoning. It was found in the Jianshangou beds of the Yixian Formation, dated to 124.5 million years ago. Additional specimens have been found in the younger Dawangzhangzi bed, dating to around 122 million years ago.

<span class="mw-page-title-main">Ornithomimosauria</span> Extinct clade of theropod dinosaurs

Ornithomimosauria are theropod dinosaurs which bore a superficial resemblance to the modern-day ostrich. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia, as well as Africa and possibly Australia. The group first appeared in the Early Cretaceous and persisted until the Late Cretaceous. Primitive members of the group include Nqwebasaurus, Pelecanimimus, Shenzhousaurus, Hexing and Deinocheirus, the arms of which reached 2.4 m (8 feet) in length. More advanced species, members of the family Ornithomimidae, include Gallimimus, Struthiomimus, and Ornithomimus. Some paleontologists, like Paul Sereno, consider the enigmatic alvarezsaurids to be close relatives of the ornithomimosaurs and place them together in the superfamily Ornithomimoidea.

<span class="mw-page-title-main">Ornithomimidae</span> Group of theropod dinosaurs

Ornithomimidae is an extinct family of theropod dinosaurs which bore a superficial resemblance to modern ostriches. Ornithomimids were fast, omnivorous or herbivorous dinosaurs known mainly from the Late Cretaceous Period of Laurasia, though they have also been reported from the Lower Cretaceous Wonthaggi Formation of Australia.

<i>Juravenator</i> Extinct genus of dinosaurs

Juravenator is a genus of small coelurosaurian theropod dinosaur, which lived in the area which would someday become the top of the Franconian Jura of Germany, about 151 or 152 million years ago. It is known from a single, juvenile specimen.

<i>Sapeornis</i> Extinct genus of dinosaurs

Sapeornis is a monotypic genus of avialan dinosaurs which lived during the early Cretaceous period. Sapeornis contains only one species, Sapeornis chaoyangensis.

<i>Yixianornis</i> Extinct genus of dinosaurs

Yixianornis is a bird genus from the early Cretaceous period. Its remains have been found in the Jiufotang Formation at Chaoyang dated to the early Aptian age, around 120 million years ago. Only one species, Yixianornis grabaui, is known at present. The specific name, grabaui, is named after American paleontologist Amadeus William Grabau, who surveyed China in the early 20th century.

<i>Anchiornis</i> Extinct genus of dinosaurs

Anchiornis is a genus of small, four-winged paravian dinosaurs, with only one known species, the type species Anchiornis huxleyi, named for its similarity to modern birds. The Latin name Anchiornis derives from a Greek word meaning "near bird", and huxleyi refers to Thomas Henry Huxley, a contemporary of Charles Darwin.

<i>Inkayacu</i> Extinct species of red-bellied penguin

Inkayacu is a genus of extinct penguins. It lived in what is now Peru during the Late Eocene, around 36 million years ago. A nearly complete skeleton was discovered in 2008 and includes fossilized feathers, the first known in penguins. A study of the melanosomes, pigment-containing organelles within the feathers, indicated that they were gray or reddish brown. This differs from modern penguins, which get their dark black-brown feathers from unique melanosomes that are large and ellipsoidal.

Dinosaur senses are difficult subjects of study for paleontologists since soft tissue anatomy rarely fossilizes.

<span class="mw-page-title-main">Dinosaur coloration</span> Studies of coloration in dinosaurs

Dinosaur coloration is generally one of the unknowns in the field of paleontology, as skin pigmentation is nearly always lost during the fossilization process. However, recent studies of feathered dinosaurs and skin impressions have shown the colour of some species can be inferred through the use of melanosomes, the colour-determining pigments within the feathers.

<span class="mw-page-title-main">Julia Clarke</span> American paleontologist

Julia Allison Clarke is an American paleontologist and evolutionary biologist who studies the evolution of birds and the dinosaurs most closely related to living birds. She is the John A. Wilson Professor in Vertebrate Paleontology in the Jackson School of Geosciences and a Howard Hughes Medical Institute Professor at the University of Texas at Austin.

References

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  2. 1 2 3 4 5 Schmitz, Lars; Motani, Ryosuke (2011-05-06). "Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology". Science. 332 (6030): 705–708. Bibcode:2011Sci...332..705S. doi:10.1126/science.1200043. ISSN   0036-8075. PMID   21493820.
  3. ↑ Larsson, HCE (2001). "Endocranial anatomy of Carcharodontosaurus saharicus (Theropoda: Allosauroidea) and its implications for theropod brain evolution". In Tanke, DH; Carpenter, K (eds.). Mesozoic vertebrate life. Bloomington, Indiana: Indiana University Press. pp.  19–33. ISBN   0-253-33907-3.
  4. 1 2 3 Stevens, Kent A. (12 June 2006). "Binocular vision in theropod dinosaurs" (PDF). Journal of Vertebrate Paleontology. 26 (2): 321–330. doi:10.1671/0272-4634(2006)26[321:BVITD]2.0.CO;2. Archived from the original (PDF) on 23 March 2012. Retrieved 2017-09-12.
  5. 1 2 Choiniere, Jonah N.; Neenan, James M.; Schmitz, Lars; Ford, David P.; Chapelle, Kimberley E. J.; Balanoff, Amy M.; Sipla, Justin S.; Georgi, Justin A.; Walsh, Stig A.; Norell, Mark A.; Xu, Xing; Clark, James M.; Benson, Roger B. J. (2021-05-07). "Evolution of vision and hearing modalities in theropod dinosaurs". Science. 372 (6542): 610–613. Bibcode:2021Sci...372..610C. doi:10.1126/science.abe7941. ISSN   0036-8075. PMID   33958472.
  6. ↑ "Dinosaurs that hunted in the dark". oumnh.ox.ac.uk. Retrieved 2024-05-02.
  7. ↑ Vinther, Jakob (2020-05-30). "Reconstructing Vertebrate Paleocolor". Annual Review of Earth and Planetary Sciences. 48 (1): 345–375. Bibcode:2020AREPS..48..345V. doi: 10.1146/annurev-earth-073019-045641 . ISSN   0084-6597.
  8. 1 2 Doucet, Stéphanie M; Meadows, Melissa G (2009-04-06). "Iridescence: a functional perspective". Journal of the Royal Society Interface. 6 (suppl_2): S115–S132. doi:10.1098/rsif.2008.0395.focus. ISSN   1742-5689. PMC   2706478 . PMID   19336344.


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