Posts tagged teeth

Black Piranha - Serrasalmus rhombus The black piranha (also known as the redeye or rhombeus piranha) has recently been discovered to have a bite force as strong as the estimated force of the extinct Megapiranha. Though the negative stigma towards piranhas is largely undeserved, the mature black piranha is one of the most aggressive fish. This is especially true recently, with the over-fishing of the Amazon and Orinoco rivers, depleting the food sources of the adult fish. Most species of juvenile piranhas feed on the scales and fins of others fish. Yes, they will swim up to, and rip the fins off of big fish, especially as they near maturity, but are not yet large enough to reliably hunt down other fish. Despite their huge size (up to 1 m long, four times longer than adult black piranhas) and extremely strong bite force, the Megapiranha of the Pleistocene era (8-10 mya) wasn’t believed to have a solely carnivorous diet. Their saw-shaped teeth bear similarities to the Serrasalmus genus, but also to the teeth of the Pacu, or “vegetarian piranha”. Expédition dans les parties centrales de l’Amérique du Sud, de Rio de Janeiro à Lima et de Lima au Para. Under direction of  Le Comte Francis de Castelnau, 1856.

Black Piranha - Serrasalmus rhombus

The black piranha (also known as the redeye or rhombeus piranha) has recently been discovered to have a bite force as strong as the estimated force of the extinct Megapiranha.

Though the negative stigma towards piranhas is largely undeserved, the mature black piranha is one of the most aggressive fish. This is especially true recently, with the over-fishing of the Amazon and Orinoco rivers, depleting the food sources of the adult fish.

Most species of juvenile piranhas feed on the scales and fins of others fish. Yes, they will swim up to, and rip the fins off of big fish, especially as they near maturity, but are not yet large enough to reliably hunt down other fish.

Despite their huge size (up to 1 m long, four times longer than adult black piranhas) and extremely strong bite force, the Megapiranha of the Pleistocene era (8-10 mya) wasn’t believed to have a solely carnivorous diet. Their saw-shaped teeth bear similarities to the Serrasalmus genus, but also to the teeth of the Pacu, or “vegetarian piranha”.

Expédition dans les parties centrales de l’Amérique du Sud, de Rio de Janeiro à Lima et de Lima au Para. Under direction of  Le Comte Francis de Castelnau, 1856.

commons.wikimedia.org

Boomslang - Bucephalus viridis [now Dispholidus typus] Where the elapids and viperids have fangs at the front of their mouth for easy envenomation, boomslangs (a member of the Colubrids) are equipped with regular teeth at the front of their mouth, and venom-injecting fangs at the back. Because of this, even though their venom is extremely hemotoxic, they rarely are able to inject enough into a larger animal (such as a human) to cause death. However, the bite of a boomslang is not to be underestimated - as it’s not always clear when the fangs have punctured the skin due to the other teeth leaving puncture wounds, medical help should always be sought out. The venom is almost completely hemotoxic, and the lack of neurotoxic symptoms can lead bite victims to believe that there was either no envenomation, or that they can just wait for their body to process the toxin. This mindset is what led to the 1957 death of esteemed herpetologist Karl Schmidt. He believed that the amount of venom he received was negligible, but 28 hours later his blood was so thin that it was coming out of every hole in the body, including his eyes and ears, and no amount of medical treatment could have saved him. Early antivenin administration is critical. Luckily, even if you’re in its natural habitat (forested areas in sub-Saharan Africa), you will probably never encounter a boomslang in the wild. They’re timid, generally dwell in trees more than 20 feet above the forest floor, and would much rather eat a small bird than waste their venom on a human. Most bites occur when someone tries to handle or kill one. Illustrations of the Zoology of South Africa: No. XXII. Andrew Smith, March 1845.

Boomslang - Bucephalus viridis [now Dispholidus typus]

Where the elapids and viperids have fangs at the front of their mouth for easy envenomation, boomslangs (a member of the Colubrids) are equipped with regular teeth at the front of their mouth, and venom-injecting fangs at the back. Because of this, even though their venom is extremely hemotoxic, they rarely are able to inject enough into a larger animal (such as a human) to cause death.

However, the bite of a boomslang is not to be underestimated - as it’s not always clear when the fangs have punctured the skin due to the other teeth leaving puncture wounds, medical help should always be sought out. The venom is almost completely hemotoxic, and the lack of neurotoxic symptoms can lead bite victims to believe that there was either no envenomation, or that they can just wait for their body to process the toxin.

This mindset is what led to the 1957 death of esteemed herpetologist Karl Schmidt. He believed that the amount of venom he received was negligible, but 28 hours later his blood was so thin that it was coming out of every hole in the body, including his eyes and ears, and no amount of medical treatment could have saved him. Early antivenin administration is critical.

Luckily, even if you’re in its natural habitat (forested areas in sub-Saharan Africa), you will probably never encounter a boomslang in the wild. They’re timid, generally dwell in trees more than 20 feet above the forest floor, and would much rather eat a small bird than waste their venom on a human. Most bites occur when someone tries to handle or kill one.

Illustrations of the Zoology of South Africa: No. XXII. Andrew Smith, March 1845.

Ways to Die: Snake Venom

The vast majority of snakes that one encounters in the wild (unless you live in Australia or India) are either non-venomous to humans or want nothing to do with you.

However, should you stumble upon a rattlesnake nest or coral snake hole while texting in the middle of nowhere, there will probably be a combination of different enzymes and polypeptides pumped into your body, via the modified parotid salivary glands (right below the ear in humans) that snakes have evolved over the ages, to disable their prey. Of course, you’re not prey, but you stepped on a snake while texting. It has every reason to envenomate you.

While all snakes have multiple active enzymes in their venom, all snakes dangerous to humans have either neurotoxins or cytotoxins as a significant component in their venom. For the most part, elapids (such as the cobras and mambas) create neurotoxins, while the viperids (such as vipers, adders, and rattlesnakes) create cytotoxins.

Neurotoxins

  • Dendrotoxins: Inhibit neurotransmission by blocking the exchange of positive and negative ions across the pre-synaptic neuronal membrane, causing paralysis. Found in some rattlesnakes (such as the Mojave) and mambas.
  • Fasciculins: Destroys acetylcholinesterase (AChE) in synaptic clefts of nerves. Without AChE, acetylcholine (ACh) is not broken down, and remains bound to the postsynaptic vesicles of the nerve, leading to constant contraction of the related muscles. This is called tetany or tetanic paralysis. Found only in mambas.
  • α-neurotoxins: Very large group of toxins that mimic ACh and bind to post-synaptic vesicles, leading to numbness and paralysis. Found in cobras, kraits, and sea snakes. 

Cytotoxins

  • Cardiotoxins: Target muscle cells and cause depolarization. If enough of these components reach the heart, the depolarization can cause irregular heartbeat or spontaneous stopping of the heart. Can cause fasciculations in skeletal muscles. Found in the Naja genus, and in King Cobras. Minor but important component of mamba venom.
  • Phospholipases: Proteins that target the phospholipid bilayer of cells, causing cellular rupture. Can cause extreme blistering at site of bite. Relatively uncommon, found in the Japanese Habu.
  • Hemotoxins: Burst red blood cells (hemolysis), causing thin blood, internal bleeding, and blood clots due to the massive clotting response. Found to some degree in almost all vipers, as well as some cobras.

Images:
Top: Bungaris fasciatus - Banded Krait. An elapid, and the largest of the kraits. Has neurotoxic venom. [source]
Center Right: Hydrophis robusta [now Hydrophis spiralis] - Yellow Sea-Snake. The longest sea snake, at 3 m (9.8 ft). A member of the Hydrophiinae, separate from other elapids. Though they have some of the most toxic venom in the world, bites are extremely uncommon and often unnoticed. [source]
Center Left: Vipera russellii - Russell’s Viper. A particularly aggressive viperid. Necrosis and amputation following envenomation not uncommon, due to hemolysis and local cell damage. [source]
Bottom: Vipera caudisona [now Crotalus horridus] - Timber Rattlesnake. A venomous viperid endemic to the United States. Primarily hemotoxic venom, very low fatality rate, but very painful bites. [source]

biomedicalephemera: Canid and Felidae Skeletons. Note the similarities in skull structure between the carnivores - forward-facing eyes with depth perception, sharp fangs, and large temporal surfaces for muscle attachment. The size of the mandibular muscles and strong vaulting of the skull affords the massive jaw strength that can be required to crunch through, at a minimum, tough skin and sinew. In the case of the hyena, the mandibles are strong enough to break up the bones of even large cattle. Das thierleben in Schönbrunn, 1904.

biomedicalephemera:

Canid and Felidae Skeletons.

Note the similarities in skull structure between the carnivores - forward-facing eyes with depth perception, sharp fangs, and large temporal surfaces for muscle attachment. The size of the mandibular muscles and strong vaulting of the skull affords the massive jaw strength that can be required to crunch through, at a minimum, tough skin and sinew. In the case of the hyena, the mandibles are strong enough to break up the bones of even large cattle.

Das thierleben in Schönbrunn, 1904.

Form and Skull of Sus scrofa moupinensis - North China wild boar

Piggers! The wild boar was domesticated in China at some point between 7000-8000 BCE, after dogs, sheep, and cats, but before cattle, horses, and camels. Wild swine are native to most of Asia, Central Europe, and North Europe, but at this point have formed feral herds throughout every continent but Antarctic. In the wild, most Suidae are very aggressive in protecting themselves and their territory, and uncastrated domestic males (boars) tend to display the same characteristics in many breeds.

As one can tell by the sharp canines and incisors, and broad canines good for grinding food, Suidae are extremely omnivorous, and find food by digging through the dirt with their snouts. In males, the canine teeth grow through their entire life, though at different rates in each genus. In feral boars (Sus scrofa), the canines don’t often reach more than a few inches long, but they are razor-sharp and expertly wielded. In some other species, such as the babirusa, the overgrown canines (tusks) are much longer than those of Sus scrofa, reaching the point of growing so long they curve backwards and into the cranial cavity.

Tusk-brains aside, all Suidae are extremely intelligent when it comes to domestic animals. As omnivores, they’re both hunted and hunters in the wild, and need to have an effective and developed brain to balance both.

Elemens de zoologie. Henri Milne-Edwards, for M. Alphonse Milne Edwards. 1840.

openlibrary.org

Love your slow loris post! I read somewhere that they have a special gland in their elbow that releases a toxin, making them the world's only venomous primate. Whoa! — Asked by carapaceshell

You point out the awesomest slow loris trait that I TOTALLY FORGOT TO PUT IN THE POST! Seriously, it’s what made me love them to begin with!

The toxin is produced in their elbow-glands (evolutionarily developed in the same fashion as the poison gland connected to the heel spur in male platypuses!), but is actually mostly-inactive before it comes in contact with the enzymes in their saliva. It’s only after it’s mixed together with the saliva and they groom themselves (and their infants) that their poison is an effective deterrent to predators.

dynamicafrica:

The earliest evidence of ancient dentistry we have is an amazingly detailed dental work on a mummy from ancient Egypt that archaeologists have dated to 2000 BCE.

The work shows intricate gold work around the teeth. This mummy was found with two donor teeth that had holes drilled into them. Wires were strung through the holes and then around the neighboring teeth.

via metalonmetalblog

metalonmetalblog

Portrayals of Dentistry in the 17th Century

I had the privilege to get a chipped filling extracted from my gingiva and to have the filling re-done earlier today, in a process that was about as fun as, well, getting an enamel chip dug out of your gums and then getting a large filling right over the seriously-inflamed gumline.

Of course, as much as I piss and moan about how much it hurt, my pain is nothing compared to people in the 17th century. Well, at least according to the artists of the era. There seems to have been a particular interest in the pain inflicted by the dentists and barber-surgeons of the time, and the fascination of the people around the “patient” in the apparent misery they’re going through.

Dentists were largely seen as below barber-surgeons until the very late 1600s-early 1700s, when one Pierre Fauchard took massive steps towards legitimization of the profession.

Top: “The Dentist” Gerard van Honthorst, 1622.
Center Left: “The Quackdoctor” Jan Steen, 1651.
Center Right: “The Extraction of Tooth” Gerard Dou, ca. 1630-1635.
Bottom: “The Toothpuller” Caravaggio (probable), ca. 1608-1610.

wga.hu

Fruit bat of the subfamily Pteropodinae The megabats of the Pteropodinae include the largest bats in the world: the Giant Golden-Crowned Flying Fox (Acerodon jubatus) and the Large Flying Fox (Pteropus vampyrus), also known as the Malaysian Flying Fox. The teeth of the family Pteropus, and especially of the subfamily Pteropodinae, are specially designed to rip open and grind up fruits, both juicy and fleshy. The large canines allow them to slash into thick skins, and the dextrous tongue and molars that are good for chewing (but not continued grinding) make an ideal dentition for most South Pacific fruits. Some fruit bats consume vegetation, pollen, or nectar, but Pteropodinae consumes almost exclusively fruit. Fruit bats lack a tail and the ability to echolocate, like all Old-World bats. They have very good eyesight, and are thought to have split off from microbats (the New-World bats, including all of the carnivorous bats) during the Eocene epoch, around 45 million years ago. Die Säugthiere in Abbildungen nach der Natur. J.C.D. Schreber, 1774.

Fruit bat of the subfamily Pteropodinae

The megabats of the Pteropodinae include the largest bats in the world: the Giant Golden-Crowned Flying Fox (Acerodon jubatus) and the Large Flying Fox (Pteropus vampyrus), also known as the Malaysian Flying Fox.

The teeth of the family Pteropus, and especially of the subfamily Pteropodinae, are specially designed to rip open and grind up fruits, both juicy and fleshy. The large canines allow them to slash into thick skins, and the dextrous tongue and molars that are good for chewing (but not continued grinding) make an ideal dentition for most South Pacific fruits. Some fruit bats consume vegetation, pollen, or nectar, but Pteropodinae consumes almost exclusively fruit.

Fruit bats lack a tail and the ability to echolocate, like all Old-World bats. They have very good eyesight, and are thought to have split off from microbats (the New-World bats, including all of the carnivorous bats) during the Eocene epoch, around 45 million years ago.

Die Säugthiere in Abbildungen nach der Natur. J.C.D. Schreber, 1774.

openlibrary.org

biomedicalephemera: […I apologize in advance] Yo dawg, I heard you like teeth, so I put some teeth in yo teeth! Child’s Book of Teeth. Harrison Wader Ferguson D.D.S., 1922.

biomedicalephemera:

[…I apologize in advance]

Yo dawg, I heard you like teeth, so I put some teeth in yo teeth!

Child’s Book of Teeth. Harrison Wader Ferguson D.D.S., 1922.

Heterocephalus glaber - Naked Mole Rat Aside from their rather unsightly appearance, naked mole rats are a very unique species of mammal. Their societies are set up much like your standard ant colonies, with a queen whose sole purpose is to give birth, and individuals who have specific duties in the colony. These include tending the queen, defending their massive labyrinth of underground tunnels, gathering food, and digging more tunnels. Their roles are largely determined at birth, and are difficult to change once the mole rat is an adult. Other cool things about naked mole rats: Their skin is remarkably impervious to pain and itching, due to a lack of proper Substance P encoding in their genes. Their lips are located *behind* their massive teeth, to protect them from damage while the rats dig. They are not truly warm-blooded like other mammals. When they get too cold, they travel upwards in the underground tunnel system, and when they get too hot, they go down into the cooler parts. They don’t need much oxygen or food and have a very slow metabolism. Their lifespan is up to 28 years, thanks to that ridiculous metabolism. Proceedings of the General Meetings for Scientific Business of the Zoological Society of London. 1885.

Heterocephalus glaber - Naked Mole Rat

Aside from their rather unsightly appearance, naked mole rats are a very unique species of mammal. Their societies are set up much like your standard ant colonies, with a queen whose sole purpose is to give birth, and individuals who have specific duties in the colony. These include tending the queen, defending their massive labyrinth of underground tunnels, gathering food, and digging more tunnels. Their roles are largely determined at birth, and are difficult to change once the mole rat is an adult.

Other cool things about naked mole rats:

  • Their skin is remarkably impervious to pain and itching, due to a lack of proper Substance P encoding in their genes.
  • Their lips are located *behind* their massive teeth, to protect them from damage while the rats dig.
  • They are not truly warm-blooded like other mammals. When they get too cold, they travel upwards in the underground tunnel system, and when they get too hot, they go down into the cooler parts.
  • They don’t need much oxygen or food and have a very slow metabolism.
  • Their lifespan is up to 28 years, thanks to that ridiculous metabolism.

Proceedings of the General Meetings for Scientific Business of the Zoological Society of London. 1885.

biomedicalephemera: 1916. Dental hut in disembarkation camp for US GIs arriving in England. The ship ride across the Atlantic unfortunately did not generally have provisions for adequate personal care of teeth, and toothaches/inflamed gums were commonplace when GIs arrived. If they didn’t improve after a few days of proper care or became very decayed/infected, the dental hut was the new enlistee’s best friend.

biomedicalephemera:

1916. Dental hut in disembarkation camp for US GIs arriving in England. The ship ride across the Atlantic unfortunately did not generally have provisions for adequate personal care of teeth, and toothaches/inflamed gums were commonplace when GIs arrived. If they didn’t improve after a few days of proper care or became very decayed/infected, the dental hut was the new enlistee’s best friend.

Front View of Muntjac Skull The muntjac is native to South Asia, but has been introduced to some parts of England, and is considered an invasive species there. The general build of this small deer is similar throughout the genus, with a short stature, short and single-pointed antlers, and tusks. Muntjacs are also considered the oldest genus of deer extant, having originated at least 30 million years ago (as compared to white-tailed and mule deer, whose direct ancestor evolved less than 5 million years ago). Despite this, and their genetic similarities on an mtDNA level, the various species of the genus are very interesting to geneticists on account of their chromosomal differences. The Indian Muntjac has a diploid number of only 7 in the males, and 6 in the females, while the Reeve’s Muntjac has a diploid number of 46. That’s a huge difference in one genus, and we’re still trying to make sense of how the species can be so similar, yet so incredibly different! The Naturalist’s Library: Vol XXI - Mammalia: Deer, Antelopes and Camels. Sir William Jardine, 1878.

Front View of Muntjac Skull

The muntjac is native to South Asia, but has been introduced to some parts of England, and is considered an invasive species there. The general build of this small deer is similar throughout the genus, with a short stature, short and single-pointed antlers, and tusks.

Muntjacs are also considered the oldest genus of deer extant, having originated at least 30 million years ago (as compared to white-tailed and mule deer, whose direct ancestor evolved less than 5 million years ago). Despite this, and their genetic similarities on an mtDNA level, the various species of the genus are very interesting to geneticists on account of their chromosomal differences. The Indian Muntjac has a diploid number of only 7 in the males, and 6 in the females, while the Reeve’s Muntjac has a diploid number of 46. That’s a huge difference in one genus, and we’re still trying to make sense of how the species can be so similar, yet so incredibly different!

The Naturalist’s Library: Vol XXI - Mammalia: Deer, Antelopes and Camels. Sir William Jardine, 1878.

Supernumerary teeth in upper palate of 15-year-old boy. Hyperdontia of unknown etiology. These extra teeth are what is known as paramolar - “along the molar”. This means that they didn’t erupt behind the regular teeth, but alongside them. In this case (and a large percentage of molar hyperdontia cases), the supernumerary teeth erupted buccally to the maxillary molars - that is, they erupted on the cheek-facing side of the upper molars. These extra teeth on the outside of the maxilla forced the normal molars inwards, and those are the teeth that you see on the hard palate of this boy. Most hyperdontia cases never even erupt, and are only visible on x-rays. In cases where the extra teeth do erupt, the most common presentation is a mesiodens - a malformed peg-like tooth between the maxillary central incisors (the upper front teeth). This boy’s case was noted by the author as highly unusual not only for the number of supernumerary teeth, but for the fact that there were multiple forms of extra teeth presented. The presentation of tuberculate (barrel-shaped) and supplemental (the same shape as the teeth in the series) teeth was denoted as a very uncommon occurrence. Surgery and Diseases of the Mouth and Jaws. Vilray Papin Blair, 1917.

Supernumerary teeth in upper palate of 15-year-old boy.

Hyperdontia of unknown etiology. These extra teeth are what is known as paramolar - “along the molar”. This means that they didn’t erupt behind the regular teeth, but alongside them. In this case (and a large percentage of molar hyperdontia cases), the supernumerary teeth erupted buccally to the maxillary molars - that is, they erupted on the cheek-facing side of the upper molars. These extra teeth on the outside of the maxilla forced the normal molars inwards, and those are the teeth that you see on the hard palate of this boy.

Most hyperdontia cases never even erupt, and are only visible on x-rays. In cases where the extra teeth do erupt, the most common presentation is a mesiodens - a malformed peg-like tooth between the maxillary central incisors (the upper front teeth). This boy’s case was noted by the author as highly unusual not only for the number of supernumerary teeth, but for the fact that there were multiple forms of extra teeth presented. The presentation of tuberculate (barrel-shaped) and supplemental (the same shape as the teeth in the series) teeth was denoted as a very uncommon occurrence.

Surgery and Diseases of the Mouth and Jaws. Vilray Papin Blair, 1917.

Tooth Extraction and Extraction Tools I don’t know a heck of a lot about dentistry, but I do know a few of the names of the extraction tools used (both back in the 1830s and today), and they’re excellent: Greyhound Cow horns Bayonet Root Elevators [I know, I know, but still can’t help but see a lift in someone’s mouth, rather than a tool meant to elevate a tooth] Traité complet de l’anatomie de l’homme comprenant la medecine operatoire, par le docteur Marc Jean Bourgery. Illustration by Nicolas Henri Jacob, 1831.

Tooth Extraction and Extraction Tools

I don’t know a heck of a lot about dentistry, but I do know a few of the names of the extraction tools used (both back in the 1830s and today), and they’re excellent:

  • Greyhound
  • Cow horns
  • Bayonet
  • Root
  • Elevators [I know, I know, but still can’t help but see a lift in someone’s mouth, rather than a tool meant to elevate a tooth]

Traité complet de l’anatomie de l’homme comprenant la medecine operatoire, par le docteur Marc Jean Bourgery. Illustration by Nicolas Henri Jacob, 1831.