A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle , rostrum , or proboscis . The wet furless surface around the nostrils of the nose of many mammals is called the rhinarium (colloquially this is the "cold wet snout" of some mammals). The rhinarium is often associated with a stronger sense of olfaction .
26-512: The mugger crocodile ( Crocodylus palustris ) is a medium-sized broad- snouted crocodile , also known as mugger and marsh crocodile . It is native to freshwater habitats from southern Iran to the Indian subcontinent , where it inhabits marshes , lakes , rivers and artificial ponds . It rarely reaches a body length of 5 m (16 ft 5 in) and is a powerful swimmer, but also walks on land in search of suitable waterbodies during
52-416: A different result. The bone that has been called the "premaxilla" (incisive bone) in mice consists of two parts: most of the bone covering the face originates from the maxillary prominence , and only a part of the palate originates from the medial nasal prominence . This may be due to the replacement of most of the incisive bone with septomaxilla in the therian mammal , as following section. In any case,
78-642: A symbol for the fructifying and destructive powers of the rivers since the Vedic period . It was first scientifically described in 1831 and is protected by law in Iran, India and Sri Lanka. Since 1982, it has been listed as Vulnerable on the IUCN Red List . Outside protected areas , it is threatened by conversion of natural habitats, gets entangled in fishing nets and is killed in human–wildlife conflict situations and in traffic accidents. Crocodilus palustris
104-415: A variety of shapes. Some animals, including ursines and great cats, have box-like snouts, while others, like shrews, have pointed snouts. Pig snouts are flat and cylindrical. Strepsirrhine primates have muzzles, as do baboons . Great apes have reduced muzzles, with the exception being human beings, whose face does not have protruding jaws nor a snout but merely a human nose . The muzzle begins at
130-1067: Is from a tip dating study, for which morphological , molecular DNA sequencing and stratigraphic fossil age data were simultaneously used to establish the inter-relationships within Crocodylidae . This cladogram was revised in a paleogenomics study. West African slender-snouted crocodile Mecistops cataphractus Euthecodon † Brochuchus † Rimasuchus † Osborn’s dwarf crocodile Osteolaemus osborni Dwarf crocodile Osteolaemus tetraspis Voay † Crocodylus anthropophagus † Crocodylus thorbjarnarsoni † Crocodylus palaeindicus † Crocodylus Tirari Desert † Freshwater crocodile [REDACTED] New Guinea crocodile Philippine crocodile Saltwater crocodile [REDACTED] Siamese crocodile [REDACTED] Mugger crocodile [REDACTED] Crocodylus checchiai † Crocodylus falconensis † West African crocodile C. suchus Snout Snouts are found on many mammals in
156-616: Is thought to have been the first species that genetically diverged from the common ancestor of the genus about 12.45 to 7.17 million years ago . The sister group comprising saltwater crocodile ( C. porosus ), Siamese crocodile ( C. siamensis ) and mugger crocodile diverged about 11.65 to 6.52 million years ago . The latter diverged from this group about 8.91 to 4.19 million years ago . A paleogenomics analysis indicated that Crocodylus likely originated in Africa and radiated towards Southeast Asia and
182-402: The incisive bone . Other terms used for this structure include premaxillary bone or os premaxillare , intermaxillary bone or os intermaxillare , and Goethe's bone . In human anatomy , the premaxilla is referred to as the incisive bone ( os incisivum ) and is the part of the maxilla which bears the incisor teeth , and encompasses the anterior nasal spine and alar region. In
208-524: The jaws of many animals, usually bearing teeth , but not always. They are connected to the maxilla and the nasals. While Johann Wolfgang von Goethe was not the first one to discover the incisive bone in humans, he was the first to prove its presence across mammals. Hence, the incisive bone is also known as Goethe's bone . Incisive bone is a term used for mammals, and it has been generally thought to be homologous to premaxilla in non-mammalian animals. However, there are counterarguments. According to them,
234-408: The nasal cavity , the premaxillary element projects higher than the maxillary element behind. The palatal portion of the premaxilla is a bony plate with a generally transverse orientation. The incisive foramen is bound anteriorly and laterally by the premaxilla and posteriorly by the palatine process of the maxilla. It is formed from the fusion of a pair of small cranial bones at the very tip of
260-402: The stop , just below the eyes, and includes the dog's nose and mouth. In the domestic dog, most of the upper muzzle contains organs for detecting scents . The loose flaps of skin on the sides of the upper muzzle that hang to different lengths over the mouth are called ' flews'. The muzzle is innervated by one of the twelve pairs of cranial nerves, which start in the brain and emerge through
286-691: The Americas, diverging from its closest recent relative, the extinct Voay of Madagascar , around 25 million years ago near the Oligocene / Miocene boundary. Within Crocodylus , the mugger crocodile's closest living relatives are the Siamese crocodile and the saltwater crocodile. Fossil crocodile specimens excavated in the Sivalik Hills closely resemble the mugger crocodile in
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#1732798497341312-498: The central part in more primitive forms. They are fused in blowfishes and absent in cartilaginous fishes such as sturgeons . Reptiles and most non-mammalian therapsids have a large, paired, intramembranous bone behind the premaxilla called the septomaxilla . Because this bone is vestigial in Acristatherium (a Cretaceous eutherian ) this species is believed to be the oldest known therian mammal. Intriguingly
338-434: The development and evolution of this region is complex and needs to be considered carefully. In bilateral cleft lip and palate , the growth pattern of the premaxilla differs significantly from the normal case; in utero growth is excessive and directed more horizontally, resulting in a protrusive premaxilla at birth. Forming the oral edge of the upper jaw in most jawed vertebrates , the premaxillary bones comprise only
364-425: The first to describe the incisive bone as a separate bone within the skull in 1779 and 1780, respectively. In the 1790s, Johann Wolfgang von Goethe began studying zoology , and formed the impression that all animals are similar , being bodies composed of vertebrae and their permutations. The human skull is one example of a metamorphosed vertebra, and within it, the intermaxillary bone rests as evidence linking
390-416: The frontal process of the maxilla; and later expands posteriorly to fuse with the alveolar process of the maxilla. The boundary between the premaxilla and the maxilla remains discernible after birth and a suture is often observable up to five years of age. It is also common in non-mammals, such as chickens, that premaxilla is derived from medial nasal prominence . However, experiments using mice have shown
416-575: The hot season. Both young and adult mugger crocodiles dig burrows to which they retreat when the ambient temperature drops below 5 °C (41 °F) or exceeds 38 °C (100 °F). Females dig holes in the sand as nesting sites and lay up to 46 eggs during the dry season. The sex of hatchlings depends on temperature during incubation . Both parents protect the young for up to one year. They feed on insects , and adults prey on fish , reptiles , birds and mammals . The mugger crocodile evolved at least 4.19 million years ago and has been
442-428: The incisive bone is a novel character first acquired in therian mammals as a composition of premaxilla derived from medial nasal prominence and septomaxilla derived from maxillary prominence . In the incisive bones, only the palatine process corresponds to the premaxilla, while the other parts are the septomaxilla . Based on this, the incisive bone is not completely homologous to the non-mammalian premaxilla. This
468-426: The nasal pits. The medial processes become the septum , philtrum , and premaxilla. The first ossification centers in the area of the future premaxilla appear during the seventh week above the germ of the second incisor on the outer surface of the nasal capsule. After eleven weeks an accessory ossification center develops into the alar region of the premaxilla. Then a premaxillary process grow upwards to fuse with
494-444: The original wolf 's in size and shape, and others in the less extreme range have shortened it somewhat (mesocephalic) as in many hounds. Premaxillae The premaxilla (or praemaxilla ) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth . In humans, they are fused with the maxilla . The "premaxilla" of therian mammals has been usually termed as
520-475: The original premaxilla of other vertebrates. This homology is, however, contended. The differences in the size and composition in the premaxilla of various families of bats is used for classification. The premaxillae of squamates are fused; this feature can be used to distinguish fossil squamates from relatives. In 1573, Volcher Coiter was the first to illustrate the incisive suture in humans. Pierre Marie Auguste Broussonet and Félix Vicq-d'Azyr were
546-445: The septomaxilla is still present in monotremes . However, embryonic and fossil studies in 2021 suggest that the incisive bone, which has been called "premaxilla" in therian mammals , has been largely replaced by septomaxilla; and that only a palatal part of the incisive bone remains a vestige of premaxilla. If this hypothesis is accurate, the bones that have been called "premaxilla" in therian mammals are not entirely homologous to
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#1732798497341572-533: The shortness of the premaxillae and in the form of the nasal openings. In Andhra Pradesh ’s Prakasam district , a 30.6 cm (12.0 in) long fossilized skull of a mugger crocodile was found in a volcanic ash bed that probably dates to the late Pleistocene . Crocodylus palaeindicus from late Pliocene sediments in the Sivalik Hills is thought to be an ancestor of the mugger crocodile. Fossil remains of C. palaeindicus were also excavated in
598-503: The skull to their target organs. Other destinations of these nerves are the eyeballs, teeth and tongue. The muzzle shape of a domestic dog ranges in shape depending upon the breed , from extremely long and thin (dolichocephalic), as in the Rough Collie , to nearly nonexistent because it is so flat (extreme brachycephalic ), as in the pug . Some breeds, such as many sled dogs and spitz types, have muzzles that somewhat resemble
624-716: The vicinity of Bagan in central Myanmar . American crocodile ( C. acutus ) Orinoco crocodile ( C. intermedius ) Cuban crocodile ( C. rhombifer ) Morelet's crocodile ( C. moreletii ) Nile crocodile ( C. niloticus ) Saltwater crocodile ( C. porosus ) Mugger crocodile Siamese crocodile ( C. siamensis ) New Guinea crocodile ( C. novaeguineae ) Philippine crocodile ( C. mindorensis ) Freshwater crocodile ( C. johnstoni ) Orinoco crocodile American crocodile Cuban crocodile Morelet's crocodile Nile crocodile Mugger crocodile Siamese crocodile Saltwater crocodile New Guinea crocodile Philippine crocodile Freshwater crocodile Below cladogram
650-442: Was hypothesized by Ernst Gaupp in 1905 and demonstrated by developmental biological- and paleontological experiments in 2021. This issue is still under debate. In the embryo, the nasal region develops from neural crest cells which start their migration down to the face during the fourth week of gestation. A pair of symmetrical nasal placodes (thickenings in the epithelium ) are each divided into medial and lateral processes by
676-627: Was the scientific name proposed by René Lesson in 1831 who described the type specimen from the Gangetic plains. In subsequent years, several naturalists and curators of natural history museums described zoological specimens and proposed different names, including: Phylogenetic analysis of 23 crocodilian species indicated that the genus Crocodylus most likely originated in Australasia about 13.72 to 8.28 million years ago . The freshwater crocodile ( C. johnstoni )
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