Welcome. In this article, I will discuss the comparative anatomy of the skull, mandible, ribs, and sternum in ox, sheep, goat, horse, and dog. Previous articles covered forelimb bones, hind limb bones, and vertebrae anatomy; you may review those for background. Let’s begin today’s topic.
I hope you have a basic idea of the osteological features of the skull bones, mandible, ribs, and sternum of an animal. If you want to memorize these osteological features, you can refer to these specific articles. You will find more videos and images in these articles.
Let’s compare the osteological features of the skull, mandible, ribs, and sternum across different animals.
I will compare animal skulls, mandibles, ribs, and sternum from different animals based on the most important osteological features. You may find additional features to compare.
What we learn here (Comparative anatomy of skull and others)
- Comparative anatomy of the skull from different animals
- Comparative anatomy of the mandible from different animals
- Comparative anatomy of ribs from different animals
- Comparative anatomy of the sternum from different animals
Let’s begin the comparison.
Comparative anatomy of the skull from different animals
Consider the following important osteological features when you compare skull bones from different animals –
Shape of skull
- Pyramidal, short, and wider in ox, sheep, and goat
- Long, four-sided in horse
- Oval, elongated shape in dog
Frontal bone
- Extensive in ox, wider in sheep and goat
- Narrower in a horse and a dog
Cornual process
- Present only in ox, sheep, and goat
Zygomatic process
- Weaker and short in ox, sheep, and goat
- Larger and strong in horse
- Highly curved, short, and thin in a dog
Orbital cavity
- The orbital cavity is complete in cattle, sheep, goat, and horse
- Incomplete in the dog
Facial crest or facial tubercle
- Presence of facial tubercle in ox, sheep, and goat
- Presence of a facial crest in a horse
- Absence of a facial crest or a facial tubercle in a dog
Interparietal bone
- Fused with the parietal and occipital bones in ox, sheep, and goat
- Single bone in a horse
- Fused with the occipital bone in the dog
“Please try to compare with the most important osteological features.”
| Features | Ox, sheep and goat | Horse | Dog |
| Shape | Pyramidal, short, wider | Long, four sided | Oval elongated |
| Frontal bone | Extensive (ox). Wider (goat) | Narrower | Narrower |
| Frontal crest | Absent | Absent | Present |
| Facial crest or tubercle | Facial tubercle | Facial crest | Absent |
| Intercornual protuberance | Present | Absent | Absent |
| Nuchal crest or tubercle | Nuchal tubercle | Nuchal crest | Nuchal crest |
| Foramen lucerum | Absent | Extensive | Present |
| Interparietal bone | Fused with parietal and occipital bone | Single bone | Fused with occipital |
| Interincissive canal | Present | Present | Absent |
| Alveolar socket for canine teeth | Absent | Present | Present |
| Supraorbital process | Present | Present | Absent |
| Orbital cavity | Complete | Complete | Incomplete |
| Palatine bone | Larger | Small | Larger |
| Zygomatic process | Weaker, short | Larger, strong | Highly curved |
| Infraorbital foremen | Long | Not so long | Short |
Comparative anatomy of the mandible from different animals
We need to consider the following important osteological features to compare the mandible from different animals like ox, sheep, goat, horse, and dog –
Body of mandible
- Short, wide, and flatter in ox, sheep, and goat
- Larger, narrow, and thicker in the horse
- Narrower and flatter in the dog
Mental foramen
- Rostard and one on each side of the mandible in ox, sheep, goat, and horse
- Two or three on each side of the mandible in a dog
Angle of mandible
- The angle of the mandible is more pronounced in ox, sheep, and goat.
- In the horse, the angle of the mandible is less pronounced.
- In the dog, the angle of the mandible is rough.
Coronoid process
- Extensive and curved caudally in ox, sheep, and goat
- Thin, curved slightly medially and caudally in the horse
- Very extensive, curved slightly laterally and then caudally
Angular process
- The angular process is absent in ox, sheep, goat, and horse, but is well-developed and projects caudally from the caudal angle of the mandible in the dog.
- The masseteric fossa is very deep and encroaches on the coronoid process in the dog.
| Features | Ox, sheep and goat | Horse | Dog |
| Fusion of two parts | Incomplete fusion of two halves | Complete fusion of two halves | Incomplete fusion of two halves |
| Body | Short, wide and flatter | Larger, narrower, thicker | Narrower, flatter |
| Alveoli of lower incisor | 8 in number | 6 in number | 6 in number |
| Alveoli of lower canine | Absent | 2 in number | 2 in number |
| Mental foramen | Rostard, One in each side | Less rostard , one in each side | 2/ 3 in each side |
| Angle | More pronounced | Less pronounced | Rough |
| Ramus | Small | Larger | Relatively small |
| Coronoid process | Extensive, curve caudally | Thin, curved slightly medially | Very extensive, slightly curved laterally |
| Angular process | Absent | Absent | Weldeveloped projected caudally from caudal angle of mandible |
| Masseteric fossa | Very shallow | Very shallow | Very deep |
| Ventral surface | Curved | More or less plan | Highly curved |
Comparative anatomy of ribs from different animals
We will look at the main bone features used to compare rib anatomy in different species.
Number of ribs in different animals
- Thirteen pairs in ox, sheep, and goat (eight sternal and five pairs asternal)
- Eighteen pairs in the horse (eight sternal, ten asternal)
- Thirteen pairs in a dog (nine pairs sternal, four pairs asternal)
Body of ribs
- Less curved, longer, wider, and flatter in ox, sheep, and goat
- More curved, band-like in a horse
- Strongly curved, narrow, and thick in the dog
Distance between the head and the tubercle of the ribs
- More distance in case of ox, sheep, and goat; less distance in horse and dog
| Features | Ox, sheep and goat | Horse | Dog |
| Numbers | 13 pairs | 18 pairs | 13 pairs |
| Body | Longer, wider flatter, less curved | More curved, band like | Strongly curved, narrow, thicker |
| Distance between head & tubercle | More distance | Less distance | Less distance |
Comparative anatomy of the sternum from different animals
To compare the anatomy of the sternum among animals such as ox, sheep, goat, horse, and dog, we will examine several important osteological features. Let us begin with the shape of the sternum.
Shape of sternum
In ox, sheep, and goat, the sternum is wider, flatter, longer, and compressed dorsoventrally.
In the horse, the sternum resembles a canoe, is compressed laterally (except the caudal part), and is flattened dorsoventrally.
In the dog, the sternum is long and compressed laterally.
| Features | Ox, sheep and goat | Horse | Dog |
| Shape | Wider, flatter, longer, compressed dorsoventrally | Like a canoe, compressed laterally (except caudal part), flattened dorsoventrally | Long, compressed laterally |
| Number of bones | 7 sternebrae | 7 sternebrae | 8 sternebrae |
Conclusion
I hope you have a good idea about the similarities and differences among the skull bones, jaw, ribs, and sternum of different animals. Now, you should be able to tell these bones apart by looking at their main features.
For further details on the comparative anatomy of these bones, attend class lectures or refer to relevant books. To deepen your understanding, you may also contact me or explore my upcoming articles on veterinary comparative anatomy.
I plan to update and enrich this topic with more information, pictures, and videos in the future, if possible.
If you notice any mistakes or have suggestions, please let me know in the comment box. Thank you for your feedback.
