Rhinos are described as large, sturdy animals with an enormous body and big head. Their big heads hover just above the ground with African rhinos grazing near the ground and Asian rhinos having their heads a bit higher to reach leaves. If an animal has a massive head (a rhino’s head can weigh 800-1000lbs) it also has a massive skull.
The biggest question when looking at rhino skulls is about their horns. Think about the size of a rhino horn. The average horn is 20 inches long (about 1 and ½ footlong subs), but some can reach 55 inches long (4.5 feet, think about your average third-grader!). So, do rhino skulls include these giant horns? What about the teeth in their skulls? Some rhinos have incisors that are five inches long! What else can we learn from rhino skulls, some from extinct species from long ago? Let’s find out about rhino skulls.
Do Rhino Skulls have Horns?
This is the most pressing question about a rhino skull, do they include the impressive horns? Think about a buffalo skull, sometimes displayed at cattle ranches or restaurant. They have large horns coming out of the sides. Other animals that have horns like these are cows, goats, sheep, and water buffalo. These horns are made of bone with a protective cover of keratin (the same thing our fingernails and hair are made of). The horns are connected to the skull with connective tissue.
Rhino horns are different. Rhino horns are made entirely of keratin and do not have a boney core. The keratin of a rhino horn is interwoven and tightly compacted making it strong and hard. So, when a rhino dies and decomposes, leaving its skull behind the keratin horn does not remain attached. An educational group called Bone Clones sells rhino skull replicates, some with horns attached so we can learn what they look like when they were alive.
How Big is a Rhino’s Skull?
Think about an 8,000lb rhino with 1000lbs of that being its head! For reference an adult horse weighs between 900-2,000lbs, so a rhinos head (just the head) is the same size as a small horse! The skull of a white rhino, the largest of the rhino species, is around 2.5 feet long, 1 foot wide and 1.6 feet tall.
How Big are the Teeth in a Rhino Skull?
Three of the five rhino species have long sharp incisor teeth that they use for protection and in fights. The Asian rhinos, greater one-horned, Sumatran and Javan, all have these large teeth that can grow to be 5 inches long! The two African rhinos do not have these teeth. Researchers look at the teeth of animals to discover lots of data. They can look at stages of tooth eruption to help determine the age of an animal, they study the tooth wear to determine its diet and they can study what is called “cementum lines” to also confirm an animals age. Rhinos have a mouth full of large teeth, mostly molars, that are used for grinding grasses, trees and fruit. They have between 24-34 teeth with some species having more teeth than others.
What can Researchers Learn from Fossils of Rhino Skulls?
In 2014, a rhino skull was found north of the Arctic circle. Finding it that far north gives us the info that the range we thought for these rhinos is much larger. This skull, from an extinct rhinoceros Stephanorhinus kirchbergensis (Jäger, 1839), also was measured to see how old it was. Carbon dating estimated that it was 48,000-70,000 years old. When they examined its teeth, they actually found fossilized food remnants and used a technique called “microwear” that suggested that these rhinos ate leaves and twigs.
In Siberia another rhino skull was discovered and researched. The skull was part of a frozen rhino mummy from long ago and was dated to be “39,140 +_ 390 years BP”. This made it clear that this mummy was from a woolly rhino. Woolly rhinos are extinct from the Pliocene and Pleistocene epochs. They are thought to have looked remarkably similar to our common rhinos today but were covered in long hair, similar to our modern-day buffalo. Painters from the Stone Age often drew these horned, hairy creatures, with some of the oldest drawings being found in France. Most of the frozen remains those scientists are studying are from Siberia where this frozen mummy was also found.
Lastly a research study from the Australian National University was comparing the sizes and conditions of rhino skulls to evaluate the effects of captivity on rhinos. They compared captive rhinos that had died with wild rhinos that had been shot. The research report describes in detail the specific characteristics of each skull. The results are important as scientists try to figure out if raising rhinos in captivity is a successful strategy for maintaining and increasing rhino populations. This study found that Indian rhinos raised in captivity were a bit smaller than in the wild. However, this did not seem to have a negative effect. The group of Javan rhinos that have been monitored at the Ujung Kulon National Park are doing well and this past year produced four new baby rhinos!
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