New Study Shows that a Number of Crocodilians Eat Fruit

They may have a blood thirsty reputation, after all, a number of species are man-eaters and all crocodiles have strong jaws and a powerful bite but a new study has revealed that a significant proportion of crocodilians eat fruit.  Nile crocodiles (Crocodylus niloticus) consume fruit as does the American alligator (Alligator mississippiensis), both species are dangerous and are known to attack people.  Surprising revelations, but it turns out that these reptiles are not entirely carnivorous.  In a study by the Wildlife Conservation Society, one that no doubt involved studying lots of crocodile poo as well as reviewing a substantial amount of literature, it seems that more than dozen crocodile species enjoy an occasional taste of fruit to go along with their normal diets of fish, mammals, amphibians, other reptiles and birds.

The Difference Between a Crocodile and an Alligator

Crocodile (top) and Alligator (bottom).

Crocodiles Dispersing Seeds

This research, which has been published in the academic publication the Journal of Zoology,  provides new insight into the possible role that crocodilians, some of which have large territories, may play in forest regeneration through digesting and passing seeds from fruits.  Some seeds and nuts are regurgitated whilst others pass through the digestive tract.  Those seeds that do and get deposited after being passed through a crocodile’s stomach and intestines, even get supplied with their very own nutrient rich pile of dung.

Chemical and mechanical scarification of seeds probably occurs in the stomach, but what effects these processes have on seed viability is unknown. Because crocodilians have large territories and undertake lengthy movements, seeds are likely transported well beyond the parent plant before being voided.  Little is known about the ultimate fate of seeds ingested by crocodilians, however, deposition sites could prove suitable for seed germination.

Eighteen Species Studied

The researchers looked at eighteen species of crocodilian ranging from the American alligator to the ferocious Nile crocodile and found thirteen of the species consumed some form of fruit and vegetable matter including a variety of berries, legumes, nuts, and grains.  Some of the plant material ingested, may have been involuntary, incidental and as a consequence of capturing and eating herbivores, however, evidence was gathered to show that plant matter was deliberately consumed and occasionally in surprisingly large quantities.

Fruit Eating Crocodiles

Despite having remained virtually unchanged since the time of the dinosaurs, much remains to be learned about how crocodilians process carbohydrates and other plant-based nutrients.  Fruit eating and the consumption of plant matter must yield some nutritional rewards for crocodilians.

Seed dispersal by reptiles is known as saurochory and it had been thought that these carnivores were incapable of digesting vegetable proteins.  However, evidence of fruit eating (frugivory), was found in more than seventy percent of the species for which there was dietary information available.  Thirty-four families and forty-six plant genera were consumed by crocodilians, the majority were fleshy fruits, how crocodiles find fruits to consume is poorly understood, but crocodiles probably find plant food by a combination of airborne and waterborne cues.  Large fruits falling into water and making a splash may also prompt crocodiles to investigate the disturbance and feed.

Probably Underreported

Commenting on the research, lead author Steven Platt of the Wildlife Conservation Society stated:

“Although underreported, fruit eating appears widespread among crocodilians.  Given the biomass of crocodiles in many subtropical and tropical wetlands and their capacity for ingesting large numbers of fruits, we consider it likely that crocodilians function as significant seed dispersal agents in many freshwater ecosystems.”

A spokes person from Everything Dinosaur suggested that seed dispersal could have been a role carried out by prehistoric crocodiles.  During the Cretaceous, Crocodyliformes and even champsosaurs could have carried out a similar function.

The spokes person said:

“This study shows that more than half the crocodilian species alive today consume fruit and other vegetable matter, it just goes to show how remarkable these reptiles are and how important these apex predators might be to the maintenance of diversity of both fauna and flora in their habitats.”

American Tourist Loses Fingers in Crocodile Attack

An American tourist playing a game of golf with some friends had his round abruptly curtailed when a crocodile bit off two of his fingers.  The fifty-year-old golf enthusiast apparently pretended to feed the predator, perhaps showing off to his mates, however, the crocodile snapped and as a result the poor chap is going to have to re-model his golf swing.

Crocodile

The incident happened on a golf course in the Mexican resort of Cancun (Yucatan peninsula).  Over the last few years, officials at the resort had become increasingly concerned about the large numbers of crocodiles that had been seen around areas frequented by tourists.  Locals are aware of the potential dangers, avoiding crocodiles, but tourists, perhaps keen to get a photograph of these large carnivores may venture too close.

The Difference Between a Crocodile and an Alligator

Crocodile (top) and Alligator (bottom).

There have been a number of incidents reported, one of the most serious occurred when a homeless man was attacked by a crocodile (believed to be a Morelet’s crocodile) on the shores of Nichupte lagoon.  The victim lost his right hand in the attack.  Police spokespersons stated at the time that there were plenty of warning signs posted indicating the presence of these reptiles and they urged people to take great care and to avoid parts of the coast where the crocodile population density was highest.

In a Stable Condition

In a statement made by Civil Protection officer Felix Diaz Villalobos, it was revealed that the golfer was in a stable condition in hospital and medics had recovered one of the severed fingers in the hope of being able to reattach it.

The officer added, that the victim was attacked after he ignored signs warning about the presence of crocodiles.

He stated:

“These animals are generally very peaceful.”

There have been calls recently to re-instate hunting of Morelet’s crocodile (Crocodylus moreletti), also known as the Mexican crocodile as populations have risen since a ban on hunting was imposed.  The area of Cancun is also home to a significant number of American crocodiles (Crocodylus acutus), a crocodile very much at home in salt water and an animal capable of growing to more than four metres in length.

These crocodiles can be found as far north as Florida, in Central America and as far south as Peru and Venezuela.  They are distinguished from other large crocodile species by having a pronounced “V” shape to their snouts.  The jaws are narrower than other large Crocodilians.  However, those jaws are still very dangerous and although their diet consists largely of fish, these reptiles will attack and are man-eaters.

A spokesperson from Everything Dinosaur said:

“It is important that people keep vigilant and take heed of any warning notices, even a relatively small crocodile is capable of inflicting serious injury.”

Checking on the Progress of a Herd of Wild Horses (Przewalski’s Horse)

The efforts of a conservation team to build up the population of Przewalski’s horses in a remote part of north-western China seem to be succeeding after the survival of a foal born last summer.  Recording the number of horses is very difficult, as even though a handful of horses will tolerant the company of humans, most run away when people get within two hundred metres of them.  However, the breeding and release programme for the Przewalski’s horse is proving to be a success.

Przewalski’s Horse

The horses, named after a Russian explorer (Nikolai Przhevalsky), once roamed much of Asia and Europe during the Stone Age but with excessive hunting and habitat loss these animals, only distantly related to domesticated horses became all but extinct in the wild.  A global conservation effort using animals kept in safari parks and zoos has enabled the numbers of horses to increase and in the latter part of the 20th Century a number of preserves and wild ranges were created allowing some of these remarkable animals to be re-introduced to the wild.  One such reserve is the 1.6 million acre West Lake National Nature Reserve in Gansu Province.  The reserve is approximately the size of the county of Devon in the United Kingdom.

Extensive Nature Reserve

This nature reserve is one of a number that have been set up around Mongolia and China, the horses being very important symbols in the folklore of these remote areas.  However, the freezing winters and very hot summers make life difficult for these tough little horses.  To help the herds survive and to get them into a fit condition for breeding extra forage is fed to the animals during the winter and scientists have worked hard to open up new water resources with the establishment of a number of new wells in the protected area.

An official, Sun Zhicheng, explained how the animals were first discovered more than 2,000 years ago telling of an ancient Chinese legend, whereby an exiled criminal came across a horse whilst on the Silk Road.  The man had been banished from the oasis of Dunhuang and whilst walking he saw one of these strange, stocky, tan-coloured horses.  He made a mannequin and put it on the path where the horse walked, one day he lay down, taking the place of the dummy and he was able to catch the horse which he offered to the Emperor.

The man lied to the Emperor (Han Wudi), claiming that the horse had jumped out of a spring, the Emperor convinced that this horse was a gift of the Gods, kept the animal.

Introducing Przewalski’s Horse

Chinese authorities have been keen to re-introduce Przewalski’s horse (pronounced she-wal-ski or pres-wal-ski) back into the wilds of China.

In 1986 China purchased eighteen of the horses from the United States, Britain and Germany and has since bred them in captivity, with their numbers growing to more than seventy.  Three years ago, groups of horses were released into the nature reserve.

Przewalski’s Horse

Stone Age survivor being slowly re-introduced to the wild.

Picture credit: Everything Dinosaur

According to Sun, numbers have slowly risen, he stated:

“Now there are 27, 16 females and 11 males.  We even registered the birth of a foal in July 2011, a new success in our re-introduction process.”

Supplementing the Diet

Przewalski’s horses require daily access to water that is within a 30-kilometre (20-mile) range and does not freeze in winter.  They also need 22 pounds (10 kilogrammes) of dry food per day, relatively close to the water.  In a region that receives less than 1.5 inches of rain per year, many of these conditions could become problematical, however, help is on hand with park officials ensuring that the grazing horses get their diet supplemented by additional feeding of alfalfa, straw and corn.

Hoping to establish a population of more than one thousand animals in the next fifty years or so, the hard-working team at the West Lake National Nature Reserve hope that they will continue to have success with the breeding programme.

To view the CollectA Przewalski’s horse model and other prehistoric mammal figures: Prehistoric Mammals Models and Figures.

Stem Cell Study of Alligators Provides Clues to Tooth Regeneration in Humans

A team of international researchers led by scientists at the University of California have been getting their teeth into the problem of tooth renewal in humans.  Their study of the toothsome American Alligator (Alligator mississippiensis), a reptile famed for its powerful bite may lead to the demise of certain aspects of dentistry, if a tooth is lost why not simply grow a replacement?

Could Alligators and Crocodiles Hold the Key to Human Tooth Renewal?

Crocodile (top) and Alligator (bottom).

Alligator Teeth

One of the fascinating aspects of the Archosauria, that’s animals such as the dinosaurs and some of today’s living archosaurs the crocodilians, is these creatures’ ability to replace teeth that are lost throughout their adult lives. Reptiles and fish have the ability to regenerate teeth if they are lost.  For example, a Great White Shark (Carcharodon carcharias), has the ability to replace teeth that are lost.  Dinosaurs are sometimes referred to as “land sharks”, because they too, had this impressive ability.  Good news for both the sharks and the tyrannosaurids for example.

After all, if T. rex lost teeth either fighting or feeding then being toothless would have been a very serious and fatal drawback.  Nobody is going to watch “Jurassic Park” to see a fourteen-metre-long apex predator lick its victims to death.

Fish and reptiles have the ability to regenerate teeth that have been lost, mammals on the other hand have much more limited dental options.  Humans for example, can renew their dentition just once, (milk teeth replaced by adult teeth).  In essence, our species has just two sets of teeth for a lifetime (diphyodont dentition).  However, new research involving the microscopic study of the structure of Alligator teeth could help scientists to learn how to stimulate tooth regeneration in humans.

Research to Understand Tooth Renewal

The research team led by pathology Professor Cheng Ming Chuong (University of Southern California), have discovered unique cellular and molecular processes which permit tooth renewal in the American Alligator.  The academic paper detailing this new research has been published in the “Proceedings of the National Academy of Sciences”.

Professor Chuong commented:

“Humans naturally only have two sets of teeth — baby teeth and adult teeth.  Ultimately, we want to identify stem cells that can be used as a resource to stimulate tooth renewal in adult humans who have lost teeth.  But, to do that, we must first understand how they renew in other animals and why they stop in people.”

Mammals evolved from reptiles, our species shares a common ancestor with the American Alligator.  We may look very different from the scaly crocodiles with their impressive teeth, but there remain similarities.  For example, like the alligator, our teeth are implanted in sockets in the dental bone.  In the human jaw there is the lingering presence of a band of epithelial tissue referred to as the dental lamina.  This same type of epithelial tissue was found to be present within the components that make up each tooth of an Alligator.

Epithelium tissue is one of four types of tissue found in the higher Animalia (muscle, connective, epithelium and nerve tissue).  This band of epithelial tissue is crucial to tooth development and growth, the research team reasoned that because crocodilians have well organised teeth with a similar form and structure to our own, their dentition would make a suitable model for studying the process of tooth replacement with the objective of finding ways in which humans could grow replacement teeth.

Assistant Professor of Pathology at the Keck School of Medicine Ping Wu, stated:

 “They [alligators] have eighty teeth, each of which can be replaced up to fifty times over their lifetime, making them the ideal model for comparison to human teeth.”

Understanding Tooth Components

Under microscopic investigation, the authors of the scientific paper found that each separate alligator tooth is actually a complex “family” of three tooth components, the functional teeth in the jaw, a replacement tooth ready to erupt to replace the tooth if and when it is lost and the dental lamina.  In essence, each tooth has components at different stages of development, tooth replacement is essentially a “conveyor belt operation”, as one member of the Everything Dinosaur team commented.  There is a smooth transition from the loss of a mature tooth to its replacement and the dental laminae seems to hold the key to this process.

Microscopic Analysis of Alligator Teeth Reveal Complex “Family of Components”

Research into alligator tooth regeneration.

Picture credit: University of Southern California – Health Sciences

University of Southern California researchers identified three developmental phases for each alligator tooth unit, comprising a functional tooth (f), replacement tooth (r) and dental lamina.  The two-headed arrow provides orientation in the mouth, the buccal direction is towards the cheek, the lingual direction is towards the tongue.

The research team have concluded that the alligator dental laminae contains what appear to be stem cells from which new replacement teeth develop.

Co-author of the study, Associate Professor Randall B. Widelitz explained:

“Stem cells divide more slowly than other cells.  “The cells in the alligator’s dental lamina behaved like we would expect stem cells to behave.  In the future, we hope to isolate those cells from the dental lamina to see whether we can use them to regenerate teeth in the lab.”

The researchers went onto demonstrate that tooth growth is speeded up by novel cellular mechanisms in response to unexpected, premature tooth loss.  Although, growing human teeth to replace adult teeth lost in trauma or as a result of disease is a long way off, the authors of this paper hope to apply the principles of alligator tooth renewal to regenerative medicine in the future.

Perhaps dentures will be redundant in the future, we will all have “crocodile smiles” instead.

For replicas and models of extinct and extant archosaurs, take a look at the Mojo Fun prehistoric life model range: Mojo Fun Prehistoric Life Models.