Instruct: Given a question, retrieve relevant documents that answer the question.
Query: What is the smallest bone in the human body?
The stapes is the third bone of the three ossicles in the middle ear. The stapes is a stirrup-shaped bone, and the smallest in the human body. It rests on the oval window, to which it is connected by an annular ligament. The stapes is described as having a base, resting on the oval window, as well as a head that articulates with the incus. These are connected by anterior and posterior limbs (). The stapes articulates with the incus through the incudostapedial joint. The stapes is the smallest bone in the human body, and measures roughly 3 x 2.5mm, greater along the head-base span.
With a mass of approximately and a length of 5 centimetres (2.0 in), the bee hummingbird ("Mellisuga helenae") is the world's smallest bird species and the smallest warm-blooded vertebrate. Called the "zunzún" in its native habitat on Cuba, it is lighter than a Canadian or U.S. penny. It is said that it is "more apt to be mistaken for a bee than a bird". The bee hummingbird eats half its total body mass and drinks eight times its total body mass each day. Its nest is 3 cm across.
The largest recorded egg is from a whale shark, and was in size. Whale shark eggs typically hatch within the mother. At and up to , the ostrich egg is the largest egg of any living bird, though the extinct elephant bird and some dinosaurs laid larger eggs. The bee hummingbird produces the smallest known bird egg, which weighs half of a gram (around 0.02 oz). Some eggs laid by reptiles and most fish, amphibians, insects and other invertebrates can be even smaller.
Ribs are classed as flat bones which usually have a protective role in the body. Humans have 24 ribs, in 12 pairs. All are attached at the back to the thoracic vertebrae, and are numbered from 1–12 according to the vertebrae they attach to. The first rib is attached to thoracic vertebra 1 (T1). At the front of the body most of the ribs are joined by costal cartilages to the sternum. The ribs connect to the vertebrae with two joints, the costovertebral joints.
"Smilodon" was around the size of modern big cats, but was more robustly built. It had a reduced lumbar region, high scapula, short tail, and broad limbs with relatively short feet. "Smilodon" is most famous for its relatively long canine teeth, which are the longest found in the saber-toothed cats, at about long in the largest species, "S. populator". The canines were slender and had fine serrations on the front and back side. The skull was robustly proportioned and the muzzle was short and broad. The cheek bones (zygomata) were deep and widely arched, the sagittal crest was prominent, and the frontal region was slightly convex. The mandible had a flange on each side of the front. The upper incisors were large, sharp, and slanted forwards. There was a diastema (gap) between the incisors and molars of the mandible. The lower incisors were broad, recurved, and placed in a straight line across. The p3 premolar tooth of the mandible was present in most early specimens, but lost in later specimens; it was only present in 6% of the La Brea sample. There is some dispute over whether "Smilodon" was sexually dimorphic. Some studies of "S. fatalis" fossils have found little difference between the sexes. Conversely, a 2012 study found that, while fossils of "S. fatalis" show less variation in size among individuals than modern "Panthera", they do appear to show the same difference between the sexes in some traits.
Besides its small size, "D. milleri" differs from other species of "Dimetrodon" in that its neural spines are circular rather than figure-eight shaped in cross-section. Its vertebrae are also shorter in height relative to the rest of the skeleton than those of other "Dimetrodon" species. The skull is tall and the snout is short relative to the temporal region. A short vertebrae and tall skull are also seen in the species "D. booneorum", "D. limbatus" and "D. grandis", suggesting that "D. milleri" may be the first of an evolutionary progression between these species.
The smallest family members are the closely related short-tailed pygmy tyrant and black-capped pygmy tyrant from the genus "Myiornis" (the first species usually being considered marginally smaller on average). These species reach a total length of and a weight of 4–5 grams. By length, they are the smallest passerines on earth, although some species of Old World warblers apparently rival them in their minuscule mean body masses if not in total length. The minuscule size and very short tail of the "Myiornis" pygmy tyrants often lend them a resemblance to a tiny ball or insect. The largest tyrant flycatcher is the great shrike-tyrant at and . A few species such as the streamer-tailed tyrant, scissor-tailed flycatcher and fork-tailed flycatcher have a larger total length (up to ), but this is mainly due to their extremely long tails; the fork-tailed flycatcher has relatively the longest tail feathers of any known bird.
The length of the adult is typically between 3mm and 6mm. The smallest known mosquitoes are around , and the largest around . Mosquitoes typically weigh around 5 mg. All mosquitoes have slender bodies with three segments: a head, a thorax and an abdomen.
Andreas Vesalius (1514-1564), a Flemish anatomist, was at first a "Galenist" at the University of Paris. When he moved to Italy and entered the University of Padua, he began dissecting human bodies. He studied many details of human anatomy and found that Galen made some anatomical mistakes. For example, Galen wrote that the sternum has seven segments, but Vesalius found it has three segments. Galen wrote that the bone of the arm is the longest bone in the human body, but Vesalius found that the bone of the thigh is actually the longest bone in human body. At age 25 Vesalius realized that the anatomical knowledge of Galen was derived from animal anatomy and therefore Galen had never dissected a human body.
The tail of "Dimetrodon" makes up a large portion of its total body length and includes around 50 caudal vertebrae. Tails were missing or incomplete in the first described skeletons of "Dimetrodon"; the only caudal vertebrae known were the eleven closest to the hip. Since these first few caudal vertebrae narrow rapidly as they progress farther from the hip, many paleontologists in the late nineteenth and early twentieth centuries thought that "Dimetrodon" had a very short tail. It was not until 1927 that a largely complete tail of "Dimetrodon" was described.
The smallest known planet is PSR B1257+12A, one of the first extrasolar planets discovered, which was found in 1992 in orbit around a pulsar. Its mass is roughly half that of the planet Mercury. The smallest known planet orbiting a main-sequence star other than the Sun is Kepler-37b, with a mass (and radius) slightly higher than that of the Moon.
The majority of squid are no more than long, although the giant squid may reach . The smallest species are probably the benthic pygmy squids "Idiosepius", which grow to a mantle length of , and have short bodies and stubby arms.
The length of the small intestine can vary greatly, from as short as to as long as , also depending on the measuring technique used. The typical length in a living person is 3m-5m. The length depends both on how tall the person is and how the length is measured. Taller people generally have a longer small intestine and measurements are generally longer after death and when the bowel is empty.
In 1983, a relatively complete skeleton was excavated from the Smokejacks pit in Surrey, Engand. These remains were described by British paleontologists Alan J. Charig and Angela C. Milner in 1986 as the holotype of a new species, "Baryonyx walkeri." After the discovery of "Baryonyx," many new genera have since been described, the majority on very incomplete remains. However, other finds bear enough fossil material and distinct anatomical features to be assigned with confidence. Paul Sereno and colleagues described "Suchomimus" in 1998"," a baryonychine from Niger on the basis of a partial skeleton found in 1997. Later in 2004, partial jaw bones were recovered from the Alcântara Formation, these were referred to a new genus of spinosaurine named "Oxalaia" in 2011 by Alexander Kellner.
Much surviving prehistoric art is small portable sculptures. It includes the oldest known representation of the human body, the Venus of Hohle Fel, dating from 40,000-35,000 BC, found in Schelklingen, Germany. It is part of a small group of female Venus figurines found in Central Europe. The Löwenmensch figurine, from about 30,000 BC, is the oldest undisputed piece of figurative art. The Swimming Reindeer of about 11,000 BCE is among the finest Magdalenian carvings in bone or antler of animals in the art of the Upper Paleolithic. At the beginning of the Mesolithic in Europe figurative sculpture greatly reduced, and remained a less common element in art than relief decoration of practical objects until the Roman period, despite some works such as the Gundestrup cauldron from the European Iron Age and the Bronze Age Trundholm sun chariot.
During the Paleolithic era (20,000-10,000 BC) humans lived in several caves above the valley floor during the summer. The caves, Schnurenloch, Mamilchloch, Zwergliloch and Chniechälebalm, contained about 5,000 bones from the now extinct cave bear which the inhabitants had butchered. While no human remains were discovered, a number of stone tools were found. Today the tools and bones are at the Historical Museum of Bern while the caves can be visited with tour groups. These caves and other nearby rock shelters continued to be used through the Neolithic, the late Bronze Age and into the Middle Ages. After the collapse of the Western Roman Empire, Alamanni tribes settled in the Simmen valley and established villages and alpine pastures.
At birth the majority of humans have 33 separate vertebrae. However, during normal development several vertebrae fuse together, leaving a total of 24, in most cases. The confusion about whether or not there are 32-34 vertebrae stems from the fact that the two lowest vertebrae, the sacrum and the coccyx, are single bones made up of several smaller bones which have fused together. This is how the vertebrae are counted: 24 separate vertebrae and the sacrum, formed from 5 fused vertebrae and the coccyx, formed from 3-5 fused vertebrae. If you count the coccyx and sacrum each as one vertebra, then there are 26 vertebrae. If the fused vertebrae are all counted separately, then the total number of vertebrae comes to between 32 and 34.
An Atom of time or "a-tom" (“indivisible” in Greek), refers to the smallest possible unit of time.
The rib cage is the arrangement of ribs attached to the vertebral column and sternum in the thorax of most vertebrates, that encloses and protects the heart and lungs. In humans, the rib cage, also known as the thoracic cage, is a bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdle to form the core part of the human skeleton. A typical human rib cage consists of 24 ribs in 12 pairs, the sternum and xiphoid process, the costal cartilages, and the 12 thoracic vertebrae.
One of the earliest occurrences of the word “atom” to mean the smallest possible unit of measuring time is found in the Greek text of the New Testament in Paul's . The text compares the length of time of the “atom” to the time needed for “the twinkling of an eye.” The text reads: “en atomo, en repe ophthamou” – the word "atom" is usually translated "a moment" - “In a moment, in the twinkling of an eye”. With that meaning it was later referred to in Medieval philosophical writings as the smallest possible division of time. The earliest known occurrence in English is in Byrhtferth's "Enchiridion" (a science text) of 1010–1012, where it was defined as 1/564 of a "momentum" (1½ minutes), and thus equal to 15/94 of a second. It was used in the "computus", the calculation used to determine the calendar date of Easter.
The fossilized remains of "Homo sapiens idaltu" were discovered at Herto Bouri near the Middle Awash site of Ethiopia's Afar Triangle in 1997 by Tim White, but were first unveiled in 2003. Herto Bouri is a region of Ethiopia under volcanic layers. According to radioisotope dating, the layers are between 154,000 and 160,000 years old. Three well preserved crania are accounted for, the best preserved being from an adult male (BOU-VP-16/1) having a brain capacity of . The other crania include another partial adult male and a six-year-old child.
These relatively small snakes rarely exceed 30 cm in length; only "Trilepida macrolepis" and "Leptotyphlops occidentalis" grow larger. The cranium and upper jaws are immobile and no teeth are in the upper jaw. The lower jaw consists of a much elongated quadrate bone, a tiny compound bone, and a relatively larger dentary bone. The body is cylindrical with a blunt head and a short tail. The scales are highly polished. The pheremones they produce protect them from attack by termites. Among these snakes is what is believed to be the world's smallest: "L. carlae" .
The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ossicles would constitute a moderate-to-severe hearing loss. The term "ossicle" literally means "tiny bone". Though the term may refer to any small bone throughout the body, it typically refers to the malleus, incus, and stapes (hammer, anvil, and stirrup) of the middle ear.
The human skeleton consists of both fused and individual bones supported and supplemented by ligaments, tendons, muscles and cartilage. It serves as a scaffold which supports organs, anchors muscles, and protects organs such as the brain, lungs, heart and spinal cord. Although the teeth do not consist of tissue commonly found in bones, the teeth are usually considered as members of the skeletal system.
The biggest bone in the body is the femur in the upper leg, and the smallest is the stapes bone in the middle ear. In an adult, the skeleton comprises around 14% of the total body weight, and half of this weight is water.
Among non-human primates phylogenesis and style of locomotion appear to play a role in apical tuft size. Suspensory primates and New World monkeys have the smallest apical tufts, while terrestrial quadrupeds and Strepsirrhines have the largest.
A study of the fingertip morphology of four small-bodied New World monkey species, indicated a correlation between increasing small-branch foraging and reduced flexor and extensor tubercles in distal phalanges and broadened distal parts of distal phalanges, coupled with expanded apical pads and developed epidermal ridges. This suggests that widened distal phalanges were developed in arboreal primates, rather than in quadrupedal terrestrial primates.