Dinosaur senses

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

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Hearing and balance

Allosaurus

The three semicircular canals of the inner ear of Allosaurus fragilis , when viewed from the side, had a subtriangular outline. [1] This subtriangular inner ear configuration is present in Carcharodontosaurus , lizards, turtles, but not in birds. [1] The pointed apex "at the junction of the anterior and posterior semicircular canals" is caused by the near linearity of the canals and closely resembles the condition of modern crocodiles. [1] The subtriangular configuration may be the basal condition of archosauromorphs. [1]

Semicircular canals tube located inside the ear

The semicircular canals or semicircular ducts are three semicircular, interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the horizontal, superior and posterior semicircular canals.

Inner ear innermost part of the vertebrate ear

The inner ear is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:

<i>Carcharodontosaurus</i> genus of carnivorous carcharodontosaurid dinosaur (fossil)

Carcharodontosaurus is a genus of carnivorous carcharodontosaurid dinosaurs that existed during the Cenomanian stage of the mid-Cretaceous Period. It is currently known to include two species: C. saharicus and C. iguidensis, which were among the larger theropods, nearly as large as or even larger than Tyrannosaurus, Giganotosaurus and Spinosaurus.

Carcharodontosaurus saharicus

The three semicircular canals of the inner ear of Carcharodontosaurus saharicus, when viewed from the side, had a subtriangular outline. [1] This subtriangular inner ear configuration is present in Allosaurus , lizards, turtles, but not in birds. [1] The semi-"circular" canals themselves were actually very linear, which explains the pointed silhouette. [1] In life, the floccular lobe of the brain would have projected into the area surrounded by the semicircular canals, just like in other non-avian theropods, birds, and pterosaurs. [2]

<i>Allosaurus</i> Genus of large theropod dinosaur

Allosaurus is a genus of carnivorous theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period. The name "Allosaurus" means "different lizard" alluding to its unique concave vertebrae. It is derived from the Greek ἄλλος/allos and σαῦρος/sauros. The first fossil remains that could definitively be ascribed to this genus were described in 1877 by paleontologist Othniel Charles Marsh. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles. Indeed, it has been a top feature in several films and documentaries about prehistoric life.

Lizard suborder of reptiles

Lizards are a widespread group of squamate reptiles, with over 6,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes the snakes and Amphisbaenia; some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3 meter long Komodo dragon.

Turtle order of reptiles

Turtles are diapsids of the order Testudines characterized by a special bony or cartilaginous shell developed from their ribs and acting as a shield. "Turtle" may refer to the order as a whole or to fresh-water and sea-dwelling testudines. The order Testudines includes both extant (living) and extinct species. The earliest known members of this group date from 220 million years ago, making turtles one of the oldest reptile groups and a more ancient group than snakes or crocodilians. Of the 356 known species alive today, some are highly endangered.

The orientation of the lagena of C. saharicus resembles the condition in crocodilians and some birds. [2] The extent of its perilymphatic duct resembled those of Varanus , crocodilians, and birds. [2] The crista which would have supported the secondary tympanic membrane in C. saharicus was either absent, or not preserved. [3]

Lagena (anatomy) Part of the ears vestibule

The lagena is a structure found in humans and in animals.

In the anatomy of the human ear, the perilymphatic duct is where the perilymphatic space is connected to the subarachnoid space. This works as a type of shunt to eliminate excess perilymph fluid from the perilymphatic space around the cochlea of the ear.

Crista Any of the inward folds of the mitochondrial inner membrane. Their number, extent, and shape differ in mitochondria from different tissues and organisms. They appear to be devices for increasing the surface area of the mitochondrial inner membrane, w

A crista is a fold in the inner membrane of a mitochondrion. The name is from the Latin for crest or plume, and it gives the inner membrane its characteristic wrinkled shape, providing a large amount of surface area for chemical reactions to occur on. This aids aerobic cellular respiration, because the mitochondrion requires oxygen. Cristae are studded with proteins, including ATP synthase and a variety of cytochromes.

Allosaurus fragilis skull. Allosaurus-crane.jpg
Allosaurus fragilis skull.

This contrasts with Troodon, whose crista were at least partiall bony. [3] The metotic strut of C. saharicus is smaller and located more closely to the midline of the animal's body than in non-avian maniraptors like Dromaeosaurus and Troodon, as well as primitive birds like Archaeopteryx and Hesperornis . [3]

<i>Archaeopteryx</i> Genus of early bird-like dinosaur

Archaeopteryx, meaning "old wing", is a genus of bird-like dinosaurs that is transitional between non-avian feathered dinosaurs and modern birds. The name derives from the ancient Greek ἀρχαῖος (archaīos) meaning "ancient", and πτέρυξ (ptéryx), meaning "feather" or "wing". Between the late nineteenth century and the early twenty-first century, Archaeopteryx had been generally accepted by palaeontologists and popular reference books as the oldest known bird. Older potential avialans have since been identified, including Anchiornis, Xiaotingia, and Aurornis.

<i>Hesperornis</i> genus of modern birds

Hesperornis is a genus of penguin-like bird that spanned the first half of the Campanian age of the Late Cretaceous period. One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an early find in the history of avian paleontology. Locations for Hesperornis fossils include the Late Cretaceous marine limestones from Kansas and the marine shales from Canada. Nine species are recognised, eight of which have been recovered from rocks in North America and one from Russia.

Theropods

Balance in theropods was aided by a vertebral column which was almost horizontal, placing the center of gravity near the hips. Tetanurans were named for their zygapophysis-stiffened tails to counterbalance long grasping claws. Deinonychosauria had elongated processes along the neural arches, which stiffened the tail and counterbalanced its long arms. Some theropods, like Tyrannosaurus rex , evolved very small arms relative to body size, which are thought, in part, to have allowed for increased head and jaw size. The middle ear cavity of troodontids and ornithomimosaurs was enlarged, suggesting sensitivity to low-frequency sounds. [4]

Tetanurae A clade that includes birds and most theropod dinosaurs

Tetanurae is a clade that includes most theropod dinosaurs, including megalosauroids, allosauroids, tyrannosauroids, ornithomimosaurs, maniraptorans, and birds. Tetanurans are defined as all theropods more closely related to modern birds than to Ceratosaurus and contain the majority of predatory dinosaur diversity. Tetanurae likely diverged from its sister group, Ceratosauria, during the late Triassic. Tetanurae first appeared in the fossil record by the Early Jurassic about 190 mya and by the Middle Jurassic had become globally distributed.

<i>Tyrannosaurus</i> Large predatory Cretaceous dinosaur

Tyrannosaurus is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex, often called T. rex or colloquially T-Rex, is one of the most well-represented of the large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 68 to 66 million years ago. It was the last known member of the tyrannosaurids, and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.

Troodon

Troodon had crista supporting its tympanic membrane that were ossified at least in their dorsal and ventral regions and their remaining portions either cartilaginous or too delicate to be preserved. [3] The metotic strut of Troodon was "laterally hypertrophied". [3] This condition resembles that of Dromaeosaurus and primitive birds like Archaeopteryx and Hesperornis . [3]

<i>Troodon</i> genus of reptiles (fossil)

Troodon is a dubious genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Cretaceous period. It includes at least one species, Troodon formosus, known from Montana. Discovered in October 1855, T. formosus was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877. Several well-known troodontid specimens from the Dinosaur Park Formation in Alberta were once believed to be members of this genus. However, recent analyses in 2017 have found the genus to be undiagnostic and referred some of these specimens to the genus Stenonychosaurus and others to the newly created genus Latenivenatrix.

Vision

Carcharodontosaurus

The optic nerve was large in Carcharodontosaurus. [5]

Theropods

Among dinosaurs, theropods had exceptionally large eyes. Deinonychosaurians, especially troodontids, had forward-facing eyes, suggesting stereoscopic vision and improved depth perception. Tyrannosauroid snouts allowed for a 55˚ binocular field of view, less than a modern human but more than their hadrosaurid prey. [4]

See also

Footnotes

  1. 1 2 3 4 5 6 7 "Description," in Larsson (2001). Pg. 23.
  2. 1 2 3 "Description," in Larsson (2001). Pg. 24.
  3. 1 2 3 4 5 6 "Description," in Larsson (2001). Pg. 25.
  4. 1 2 Fastovsky & Weishampel 2009, p.198.
  5. ↑ "Description," Larsson (2001). Page 22.

Related Research Articles

Theropoda group of dinosaurs

Theropoda or theropods are a dinosaur suborder that is characterized by hollow bones and three-toed limbs. They are generally classed as a group of saurischian dinosaurs, although a 2017 paper has instead placed them in the proposed clade Ornithoscelida as the closest relatives of the Ornithischia. Theropods were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores, omnivores, piscivores, and insectivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago (Ma) and included the sole 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.

Troodontidae family of reptiles (fossil)

Troodontidae is a family of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discoveries of complete and articulated specimens, have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like Sinovenator, demonstrate striking anatomical similarities with Archaeopteryx and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves.

Dromaeosauridae family of reptiles (fossil)

Dromaeosauridae is a family of feathered theropod dinosaurs. They were generally small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek δρομεῦς meaning 'runner' and σαῦρος meaning 'lizard'. In informal usage they are often called raptors, a term popularized by the film Jurassic Park; a few types include the term "raptor" directly in their name and have come to emphasize their bird-like appearance and speculated bird-like behavior.

<i>Dromaeosaurus</i> genus of reptiles (fossil)

Dromaeosaurus is a genus of theropod dinosaur which lived during the Late Cretaceous period, sometime between 76.5 and 74.8 million years ago, in the western United States and Alberta, Canada. The type species is Dromaeosaurus albertensis, which was described by William Diller Matthew and Barnum Brown in 1922.

<i>Protoavis</i> genus of dinosaurs

Protoavis is a problematic dinosaurian taxon known from fragmentary remains from Late Triassic Norian stage deposits near Post, Texas. Much controversy remains over the animal, and there are many different interpretations of what Protoavis actually is. When it was first described, the fossils were described as being from a primitive bird which, if the identification is valid, would push back avian origins some 60-75 million years.

<i>Stenonychosaurus</i> genus of reptiles (fossil)

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 C.M. 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 dubious Troodon in 2017 by Evans et al. and also later in the same year by Van der Reest and Currie.

Coelurosauria suborder of reptiles (fossil)

Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.

<i>Saurornithoides</i> genus of reptiles (fossil)

Saurornithoides is a genus of troodontid maniraptoran dinosaur, which lived during the Late Cretaceous period. These creatures were predators, which could run fast on their hind legs and had excellent sight and hearing. The name is derived from the Greek stems saur~ (lizard), ornith~ (bird) and eides (form), referring to its bird-like skull.

<i>Sigilmassasaurus</i> genus of reptiles

Sigilmassasaurus is a genus of tetanuran theropod dinosaur that lived approximately 100 to 94 million years ago during the middle of the Cretaceous Period in what is now northern Africa. Sigilmassasaurus was a moderately-built, ground-dwelling, bipedal carnivore, like most other theropods.

Avialae clade of dinosaurs containing all modern birds

Avialae is a clade of flying dinosaurs containing the only living dinosaurs, the birds. It is usually defined as all theropod dinosaurs more closely related to modern birds (Aves) than to deinonychosaurs, though alternative definitions are occasionally used.

Paraves Clade of all dinosaurs which are more closely related to birds than to oviraptorosaurs

Paraves are a widespread group of theropod dinosaurs that originated in the Late Jurassic period. In addition to the extinct dromaeosaurids, troodontids, anchiornithids, and scansoriopterygids, the group also contains the avialans, among which are the over ten thousand species of living birds. Primitive members of Paraves are well-known for the possession of an enlarged claw on the second digit of the foot, which was held off the ground when walking in some species.

<i>Mahakala omnogovae</i> genus of reptiles (fossil)

Mahakala is a genus of basal dromaeosaurid dinosaur from the Campanian-age Upper Cretaceous Djadokhta Formation of Ömnögovi, Mongolia. It is based on a partial skeleton found in the Gobi Desert. Mahakala was a small dromaeosaurid, and its skeleton shows features that are also found in early troodontids and avialans. Despite its late appearance, it is among the most basal dromaeosaurids. Its small size, and the small size of other basal deinonychosaurians, suggests that small size appeared before flight capability in birds.

<i>National Geographic Dinosaurs</i> book by Paul Barrett

National Geographic Dinosaurs is a nonfiction reference book on dinosaurs, written by Paul Barrett, with illustrations by Raúl Martín, and an introduction by Kevin Padian. It was published in 2001 by National Geographic.

<i>Sebecus</i> species of crocodylomorph

Sebecus is an extinct genus of sebecid crocodylomorph from Eocene of South America. Fossils have been found in among others Patagonia. Like other sebecosuchians, it was entirely terrestrial and carnivorous. The genus is currently represented by a single species, the type S. icaeorhinus. Several other species have been referred to Sebecus, but were later reclassified as their own genera.

Dinosaur intelligence

Dinosaur intelligence has been a point of contention for paleontologists. Non-avian dinosaurs were once regarded as being unintelligent animals but have largely been appraised more generously since the dinosaur renaissance. This new found optimism for dinosaur intelligence has led to highly exaggerated portrayals in pop-cultural works like Jurassic Park. Paleontologists now regard dinosaurs as being very intelligent for reptiles, but generally not as smart as their avian descendants. Some have speculated that if the Cretaceous–Paleogene extinction event had not occurred, the more intelligent forms of small theropods might have eventually evolved human-like levels of intelligence. Popular misconceptions of dinosaur neurology include the concept of a second brain in the pelvis of stegosaurs and sauropods.

Timeline of troodontid research paleozoology timeline

This timeline of troodontid research is a chronological listing of events in the history of paleontology focused on the troodontids, a group of bird-like theropod dinosaurs including animals like Troodon. Troodontid remains were among the first dinosaur fossils to be reported from North America after paleontologists began performing research on the continent, specifically the genus Troodon itself. Since the type specimen of this genus was only a tooth and Troodon teeth are unusually similar to those of the unrelated thick-headed pachycephalosaurs, Troodon and its relatives would be embroiled in taxonomic confusion for over a century. Troodon was finally recognized as distinct from the pachycephalosaurs by Phil Currie in 1987. By that time many other species now recognized as troodontid had been discovered but had been classified in the family Saurornithoididae. Since these families were the same but the Troodontidae named first, it carries scientific legitimacy.

<i>Jianianhualong</i> genus of reptiles

Jianianhualong is a genus of troodontid theropod dinosaur from the Early Cretaceous of China. It contains a single species, Jianianhualong tengi, named in 2017 by Xu Xing and colleagues based on an articulated skeleton preserving feathers. The feathers at the middle of the tail of Jianianhualong are asymmetric, being the first record of asymmetrical feathers among the troodontids. Despite aerodynamic differences from the flight feathers of modern birds, the feathers in the tail vane of Jianianhualong could have functioned in drag reduction whilst the animal was moving. The discovery of Jianianhualong supports the notion that asymmetrical feathers appeared early in the evolutionary history of the Paraves.

Anchiornithidae family of dinosaurs

Anchiornithidae is a family of eumaniraptorans which could be the basalmost family of birds in the clade Avialae. Anchiornithids have been classified at varying positions in the maniraptoran tree, with some scientists classifying them as a distinct family, a basal subfamily of Troodontidae, members of Archaeopterygidae, or an assemblage of dinosaurs that are an evolutionary grade within Avialae or Paraves.

References

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