Skeletal Identification of Mammalian Species
The specimen I studied for this project was the skeleton of a juvenile male raccoon. This specimen was a sub-adult, so it was slightly more difficult to discern specific bones due to the epiphyses and lack of ossified adult bones. The tail, along with the hand and foot bones were key points in deciding the species of the specimen. The size of the bones also played a great part in the decision of species as well. After careful examination of the skeleton, I received confirmation that the specimen is indeed a juvenile raccoon and that its sex was male.
The common raccoon, known as Procyon lotor, is a creature that most people think of as a nuisance. They are carnivorous vertebrates, and they are the most recognized mammal of the Procyonidae family. Other members of this family include kinkajous, coatis, and ringtails. This family of mammals is typically referred to as the smaller cousins of bears, and the common raccoon is actually part of the nocturnal mammal genus, Procyon, which is comprised of three different raccoon species. The common raccoon can be found virtually anywhere in the United States.
These scavenging creatures are known by most as the pest that goes through their garbage cans late at night. However, this is one of the only ways that the raccoon can sustain itself. While they can eat other small animals such as fish, frogs and bird eggs, trash is readily available in neighborhoods where raccoons are typically found. This leads to the raccoon relying on trash as its main food source, because of its ample availability and the fact that the raccoon does not need to use its energy to catch something to eat.
The raccoon tends to stay in areas where it can readily find food. This can be a neighborhood, the city, or around populated rural settings. When a raccoon becomes accustomed to having food at their fingertips on garbage night, it would not make much sense for them to leave and go somewhere where they are forced to catch their food. The raccoon likes to live a lowkey lifestyle that does not require much energy. When they are not scavenging for food, raccoons can be found sleeping anywhere they can find shelter. This can include holes in trees, under porches, abandoned (or sometimes not abandoned) cars, and even dumpsters, which are the ideal raccoon bed and breakfast.
The raccoon gets its name from the Algonquian language, which is spoken in parts of French-Canada. Its name means “he who scratches with his hands”, however other translations include the word “washer” in the translation. This relates to the fact that raccoons, while they are not opposable, do have thumbs, which makes for a dexterous hand for the animal. Their hands are the reason they are so clever and explains how they can get into trash cans easily. They are also known to wash their food before eating it, or as it may seem to us. However, they do not “wash” their food to make it clean for consumption, they simply wet it as to stimulate more nerve endings in their paws when they are holding it.
Their hands are one of the most distinctive features of raccoons, rather than their marking which include a mask over their eyes and a ringed tail. When examining the skeleton, the hands played a large part in identification. The hands and feet were the hardest parts to identify, but the elongated metatarsals, even for a juvenile, were a telltale sign that this was a raccoon. Identification of teeth also assisted the recognition that it was a raccoon. Since they are carnivores, they do have canine teeth, as well as molars. The size of this specimen, along with the teeth, the tail size and the hand/feet bones were all signs that this was indeed a raccoon.
The condition of this skeleton was not perfect; however, it was suitable for identifying the species and for adequate study of the components. The larger bones in this specimen were missing their identifying ends, which played another part in the puzzle. Both femurs were missing their lateral and medial condyles, as well as the head that fits into the acetabulum of the pelvis. The identifying features on these fragmented bones were the greater and lesser trochanter. When identifying the upper half of the skeleton, it became apparent that, while both scapulae were in perfect condition, there was no clavicle. The lack of the clavicle was not verified by age, but rather it may have been fragmented to the point that it was indistinguishable.
The fragmented ends of the femur along with the rest of the bone.
Another prominent structure missing was the sternum. All 13 rows of ribs were present; however, the presence of their conjoining structure was nonexistent. The absence of this feature was understandable, as this raccoon was very young when it died. In humans, the sternum takes 25 years, on average, to ossify, and sometimes longer. There have also been cases where the entire plate remains unossified in old age. The juvenile aspect of this raccoon had to be kept in mind when understanding why specific bones may be missing or nonexistent.
The raccoon skeleton could have easily been mistaken for another carnivore of the same size, like a house cat. The tail length, as well as the teeth, are very similar between these two animals. These two animals are actually similar enough that some people have come to believe that they can mate with each other and create cat-raccoon hybrid young. It is known for the two species to copulate on occasion; however, it is not possible for the act to produce any results.
All carnivores are known to share similar characteristics, especially when it comes to physical features. All carnivores have canine teeth, meant for tearing and cutting meat when they are eating. Another feature that is present in carnivores is sharp claws. These can be used for protection, as well as for injuring prey and ripping meat off of the bone. These features are necessary when the diet consists mainly of tough, raw meat.
The family that the raccoon belongs to is Procyonidae, which consists of animals known as the smaller cousins of bears. The raccoon’s relatives in this family are the kinkajou, coatis, and olingos. The raccoon’s lesser-known counterparts from this family are arboreal and primarily inhabit the continent of South America. Kinkajous are known to be elusive, nocturnal mammals and they are seldom seen by humans, although they are known to be distributed quite heavily through their geographical region. They are referred to by many names, including honey bear, lion bear, and bear-monkey. Coatimundis primarily inhabit South America, but have also been seen in the Southwestern portion of the U.S. They are approximately the size of a house cat, and have a ringed tail, similar to the raccoon. This animal is known to be very intelligent, just like the raccoon. Olingos also have a slightly ringed tail and are nocturnal like their relatives. These small animals are known to only weigh 2-3 pounds and can be observed sleeping in trees during the day, and eating fruit, especially figs, at night. The similarities between these species are distinct, and it can be seen why they would be referred to as small cousins of the bear, based on their physical appearance.
The raccoon relies heavily on its nervous system, and this certainly is the reason for their intelligence. Raccoons have surpassed dogs and cats in intelligence tests, and they are known to rank closer to monkeys. When eating, raccoons are known to use their hands to open things, such as cans and containers. As mentioned before, raccoons also wet their food in order to perceive it with greater accuracy through the nerve ending in their hands. This plays into the skeletal setup of their hands, as well as their muscle and motor coordination used to pick things up and use their hands for things other mammals are not able to.
The raccoon is an exceptionally interesting creature, with its elevated intelligence and mischievous nature. Getting the opportunity to see the skeleton of one was a very helpful experience, to understand how their body works and their developmental pattern. Putting the skeleton together was like a puzzle. It was a better learning experience than seeing a fake bone in a classroom that looks untouched, since they are almost never found in that state. It was interesting to study a real skeleton, with pieces missing and its imperfections.
|Skull||1 Present2 Dentary Jawbones, Unfused31 Loose Teeth|
|Vertebrae||6 Cervical Vertebrae + Axis13 Thoracic Vertebrae7 Lumbar Vertebrae10 Caudal Bones|
|Thoracic Cavity||26 Ribs (13 Pairs)Sternum = Not Present|
|Pectoral Girdle||2 ScapulaeClavicle = Not Present|
|Upper Arm||2 Humerus Bones|
|Forearm||2 Radius Bones2 Ulna Bones|
|Pelvic Girdle||2 Pelvic Bones (Ilium/Ischium)1 Sacrum|
|Thigh||2 Femurs + Fragmented Condyles|
|Lower Leg||2 Tibia Bones2 Fibula Bones|
|Miscellaneous/Unidentified||1 bag = Claw Remnants1 bag = Misc./Unidentified|
Abraira, V., & Ginty, D. (2013). The Sensory Neurons of Touch. Neuron, 79(4), 618-639. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3811145/
Bittel, J. (2017, December 04). Which animals are smartest: Dogs, cats, or … raccoons? https://www.washingtonpost.com/news/animalia/wp/2017/12/04/which-animals-are-smartest-cats-dogs-or-raccoons/
Raccoon. (2018, September 21). Retrieved from https://www.nationalgeographic.com/animals/mammals/r/raccoon/