Автор Тема: Зрение тираннозавра  (Прочитано 22468 раз)

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Оффлайн Влад

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Re: Зрение тираннозавра
« Ответ #90 : Август 20, 2018, 14:01:51 »
Прежде, чем принимать на достоверность ту или иную новость, всегда нужно искать первоисточник, в данном случае -опубликованную статью в научном издании. Если таковой нет, то это всего-лишь очередная басня "жёлтой" прессы, пусть даже и весьма правдоподобная на первый взгляд.

А если есть?
Estimating the Stereo Acuity of Tyrannosaurus—In addition
to their great size, the eyes of Tyrannosaurus were broadly separated
within the cranium. The pupils are assumed to have been
approximately in the plane of the skull, with OA  90° or less,
and capable of clear vision past the lacrimals, resulting in an
interpupillary separation of about 400 mm, compared to about
65 mm for a human. What binocular capabilities might have been
achieved by a visual system of this scale?
A measure of binocular acuity is the ‘limiting far point’ (Ogle,
1962), the greatest distance at which an object can be viewed as
distinguished from infinity. The limiting distance D can be expressed
in terms of the interpupillary separation I and the threshold
binocular disparity t
, according to the following expression,
which has been applied to avian stereopsis (McFadden, 1993):
D  I/2 / tan(t
For human vision this equation predicts D  1.3 km for an
estimate of t  10 (Reading, 1983). Objects closer than this
limiting far point will appear to stand out in depth relative to,
say, the horizon. To readily break camouflage, objects must be
substantially closer than this distance.
To estimate the limiting far point for Tyrannosaurus, an avian
form of stereopsis will be assumed, whereupon the disparity
threshold of t for Tyrannosaurus would have been substantially
coarser than its visual acuity. In the pigeon t is ∼9.5 (McFadden,
1993), about 6 times coarser than its visual acuity (Hodos et
al., 1976). In the falcon, while t has not been measured, stereopsis
is most sensitive for disparities between 8–12 (Fox et al.,
1976), which is 60 times coarser than its visual acuity.
The disparity threshold t for Tyrannosaurus can be estimated
as the product of the estimated visual acuity MAR and the assumed
/MAR ratio. Using the ostrich model for acuity (MAR
 1.6) and the pigeon model for the t
/MAR ratio, Tyrannosaurus
would have had a disparity threshold t  9.6, similar to
that of the pigeon. The computed limiting far point D is ∼140 m,
a distance of some utility for predation and locomotion.
Using the eagle model for visual acuity (MAR  0.039) and
the falcon for t
/MAR results in t  2.3 and D is ∼0.6 km. This
is a direct scaling of the optics and the stereopsis processing of a
modern raptor to the eye size and interpupillary separation of
Tyrannosaurus. Finally, it is not unreasonable to substitute the
finer t
/MAR ratio of the pigeon for that of the falcon, which
yields t  0.23 and a remarkable limiting far point of about 6
km, substantially better than human ability.
The potential visual superiority of Tyrannosaurus probably
extended beyond spatial acuities. Rowe (2000) concluded, on the
basis of the Extant Phylogenetic Bracket method (Witmer,
1995), that dinosaurs may have had color vision based on four
cone types, and color contrast enhancements provided by pigmented
oil droplets—features that permit better color perception
than that achieved by mammals. One might therefore envision
an alert, hungry Tyrannosaurus rex, raising its head to maximum
height, its keen olfactory sensitivity catching the scent of
living prey and not just carrion (Farlow, 1994; Brochu, 2000;
Farlow and Holtz, 2002), then using its vision to segregate the
prey from the background vegetation on the basis of stereopsis,
detected prey movements, and subtle color contrasts.
The binocular capabilities provided by a BFoV 55º wide and
broadly separated, large eyes (with acuities perhaps better than
human) would allow not only observation of distant prey, but
also accurate perception of the three-dimensional arrangement
of potential obstacles to avoid during pursuit predation (Farlow
et al., 1995). For ambush predation, these binocular and spatial
acuities would have been more than adequate for judging the
timing and direction of a terminal lunge. For obligate scavenging,
these visual acuities would have been superfluous.
In summary, given (1) the strong correlation between (at least
limited) binocular depth perception in those extant vertebrates
possessing more than roughly 20º overlap (and full stereopsis in
those vertebrates with about twice that amount), (2) the correlation
between BFoV width and spatial ability (e.g., cursoriality),
and (3) the extent of the remodeling of the cranium required to
achieve a BFoV of 55º or greater, it would seem most parsimonious
to conclude that the coelurosaurs included in this study all
achieved functional stereopsis and all used that capability for
spatially demanding tasks. In particular, due to its great scale and
broad frontal vision, Tyrannosaurus rex, of all sighted observers
to have ever lived, might have experience

Бред всё равно бред.

Оффлайн василий андреевич

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Re: Зрение тираннозавра
« Ответ #91 : Август 20, 2018, 18:45:00 »
Относительно органики возрастом сотни миллионов лет - кто-то серьезно об этом пишет?
А если так. Углерод замещен кремнием. Водородных связей нет. Но есть искаженная структура того, что было геномом.???  Кто-то сотни дисеров настрочочит. Ведь тут верить = не верить

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Re: Зрение тираннозавра
« Ответ #92 : Март 23, 2020, 20:23:27 »
Одна из гипотез-что у тираннозавра были развитые хиазмы, благодаря чему он имел бинокулярное зрение. 3d модель мозга динозавра есть в этой статье https://dinobook.ru/dino/xishhniki/tirannozavr