Have you ever stopped to consider just how different animals are built? Recently, I acquired a fascinating piece of natural history – a giraffe cannon bone. This remarkable bone offers a tangible way to explore the incredible variations in anatomy across species, particularly when we compare a giraffe to a human.
Alt text: Labeled illustration comparing giraffe and human limb bones, highlighting the humerus, radius, ulna, carpals, metacarpals, femur, tibia, fibula, tarsals, and metatarsals to visually represent skeletal similarities and differences.
The cannon bone in ungulates, like giraffes, is a fascinating example of bone fusion. In the forelimbs, it’s formed from the fused metacarpals, and in the hindlimbs, from fused metatarsals. The giraffe cannon bone I possess is from the right forelimb. Specifically, it’s composed of the fused 3rd and 4th metacarpals. To put this in human terms, these are the bones in your hand that lead to your middle and ring fingers. Imagine those bones, but significantly elongated and fused together! In the image above, you can see a diagram illustrating the giraffe limb bones and their human counterparts, providing a clear visual comparison.
Alt text: Close-up photograph of the proximal ends of a giraffe cannon bone, showcasing the detailed bone structure and circular holes drilled for potential mounting, as referenced in Rios et al. (2016).
Initially, determining that it was a right forelimb cannon bone required some investigation. Thanks to detailed figures and descriptions in Rios et al. (2016), a study accessible through Palaeontologia Electronica, the identification became clear. The rather prominent and perfectly round holes at each end of the bone are man-made. They were likely drilled for mounting the bone, perhaps for display. Initially, I wondered if these holes served a purpose in bone preparation, like marrow extraction during cleaning. However, these holes are located in the spongy trabecular bone at the bone ends and do not intersect the main marrow cavity.
This exploration into giraffe anatomy follows a previous comparison I made between Brachiosaurus and human metacarpals. This time, however, having a real giraffe bone in hand makes the comparison to human anatomy even more striking. It naturally leads to the question: how does the size of a giraffe’s bone truly stack up against our own?
Alt text: Comparative image showing the scale difference between a giraffe cannon bone, a Brachiosaurus metacarpal, and a human hand metacarpal, emphasizing the significant size variation across species.
Indeed, let’s visualize this size difference. The giraffe cannon bone measures an impressive 75.5cm in length. In comparison, the brachiosaur metacarpal, while substantial, is shorter at 57cm, which is about 75.5% of the giraffe bone’s length. The image above illustrates these bones scaled accurately against a human hand, immediately highlighting the vast disparity in size. While my hands appear different sizes in the photo due to perspective, the bone scale is accurate, demonstrating the importance of reliable scale indicators in visual comparisons.
Alt text: Photograph of a person standing next to a large Brachiosaurus humerus cast, emphasizing the immense size of this dinosaur bone and providing scale for comparison against human size.
The brachiosaur from Potter Creek, Colorado, is known for its massive size, being among the largest brachiosaurs globally. However, even this giant’s bones are dwarfed in relative proportion when considering the incredible stature of a giraffe. While my giraffe bone isn’t from a record-breaking animal, it still represents an animal of significant size. World-record giraffes can reach heights of around 19 feet (5.8m). Based on skeletal proportions, a giraffe of that size would likely have a metacarpal cannon bone approaching 90cm in length. This suggests my cannon bone came from a giraffe that was likely between 15.5 and 16 feet tall (4.7-4.9m) – still a towering creature.
The journey of this bone to a natural history store like Necromance remains a bit of a mystery. It likely originated from an estate sale or a similar source. During my first visit to Necromance, I observed several real giraffe bones on display, including two cannon bones and a cervical vertebra. It seems these unique specimens have since found homes with anatomists, with fellow researchers acquiring the other cannon bone and the cervical vertebra.
The giraffe cannon bone serves as a compelling reminder of the incredible diversity in animal anatomy and scale. Comparing it to a human hand bone brings the sheer size difference into sharp focus, highlighting the remarkable adaptations that allow giraffes to thrive in their environment. Stay tuned for more anatomical explorations and perhaps further dives into the world of sauropods!
Reference
Ríos M, Danowitz M, Solounias N. 2016. First comprehensive morphological analysis on the metapodials of Giraffidae. Palaeontologia Electronica 19(3):1–39. https://palaeo-electronica.org/content/2016/1702-the-metapodials-of-giraffidae
