What is the Difference Between Prosimians and Anthropoids

The main difference between prosimians and anthropoids is that prosimians are primitive primates that are small in size, and bushbabies of Africa, the lemurs of Madagascar, and the lorises, pottos, and tarsiers of Southeast Asia, whereas anthropoids are bigger-brained monkeys, apes, and humans. Furthermore, prosimians appeared around 55 million years ago, while anthropoids appeared around 35 million years ago. Moreover, prosimians are nocturnal while anthropoids are diurnal. 

In brief, prosimians and anthropoids are two groups of primates descended from tree-dwellers. Generally, they show adaptations to brachiation such as the rotating shoulder joint, a big toe and thumb that are widely separated from other toes or fingers, and stereoscopic vision. 

Key Areas Covered 

1. Prosimians
     – Taxonomy, Characteristics, Behavior
2. Anthropoids
     – Taxonomy, Characteristics, Behavior
3. What are the Similarities Between Prosimians and Anthropoids
     – Outline of Common Features
4. What is the Difference Between Prosimians and Anthropoids
     – Comparison of Key Differences

Key Terms 

Anthropoids, Haplorhini, Nocturnal, Primates, Prosimians, Strepsirrhini

Prosimians – Taxonomy, Characteristics, Behavior 

Prosimians are the primitive primates whose members belong to both Strepsirrhini and Haplorhini suborders of the order Primates. They include four infraorders, two from each suborder. The two infraorders from the suborder Strepsirrhini include Lemuriformes (lemurs, lorises, and bushbabies) and Adapiformes  (extinct “lemur-like” primates). And, the two infraorders from the suborder Haplorhini include Tarsiiformes  (tarsiers) and Omomyiformes  (extinct “tarsier-like” primates). 

Figure 1: Brown Lemur

Of these, if you take strepsirrhines, they have small brains in comparison to their body size. However, their brains also have large olfactory lobes, which give an increased sense of smell. In addition to these features, they also can sense pheromones through their vomeronasal organ. Also, they have increased night vision due to the presence of a reflective layer. In the case of lemuriforms, they have a toothcomb, a specialized set of teeth in the front, lower parts of the mouth are mostly used for combing fur. On the other hand, one of the key features of prosimians is the presence of two laterally flattened toilet claws used for grooming. Besides, lemurs and lorises use the second toe for the purpose while tarsiers use second and third toes.  

Anthropoids – Taxonomy, Characteristics, Behavior 

Anthropoids are the higher primates, excluding prosimians. Generally, they are also known as simians. However, they belong to the infraorder Simiiformes or flat-nosed primates under the suborder Strepsirrhini of the order Primates. Meanwhile, the two parvorders of anthropoids are Patyrrhini and Catarrhini. Of these two, the parvorder Patyrrhini includes New World monkeys while the parvorder Catarrhini includes the two superfamilies: Cercopithecoidea (Old World monkeys) and Hominoidea (apes), including the genus Homo.  New World monkeys originated 40 million years ago in South America, while the remaining simians split into Old World monkeys and apes around 25 million years ago. 

Figure 2: A Catarrhine (Chimpanzee) and A Platyrrhine (Red-Faced Spider Monkey)

Moreover, platyrrhines include flat-nosed primates while catarrhines include hooked-nose primates. Also, the nostrils of platyrrhines are farther apart and they point outward while the nostrils of catarrhines are closer together and they point down. In addition to these featural differences, platyrrhines have a large body size in comparison to catarrhines. Besides, the New World monkeys of the family Atelidae are the only primates having a prehensile tail. In comparison to this, Old World monkeys have shorter, non-grasping tails while apes lack tails.  

Similarities Between Prosimians and Anthropoids  

• Prosimians and anthropoids are the two groups that make up the order  Primates.  
• They descended from tree-dwellers. Therefore, they have an arboreal lifestyle.    
• Thus, they show adaptations to brachiation such as the rotating shoulder joint, a big toe and thumb that are widely separated from other toes or fingers, and stereoscopic vision.  
• Other significant characteristics include increased brain size, visual acuity, color vision,  altered shoulder girdle,  and dexterous hands.    
• They have four limbs.    
• In addition to these, they have claws modified into flattened nails and a trend toward holding the body upright.    
• They take a longer time to mature and have longer lifespans.  
• Moreover, they are sexually dimorphic with differences, including muscle mass, fat distribution, pelvic width,  canine tooth size, hair distribution, and coloration.  
  
• Typically,  they produce only one offspring per pregnancy.  
• Their gestation time is long, with an extended period of juvenile growth and period of maternal investment and care.  
• They are omnivores, consuming small invertebrates, fruits, and plants.  

Difference Between Prosimians and Anthropoids 

Definition 

Prosimians refer to the primitive primates characterized by nocturnal habitats, a long face with a moist snout, etc. while anthropoids refer to the primates characterized by a relatively flat face, dry nose, etc. 

Classification – Suborders 

Moreover, Prosimians belong to both Strepsirrhini and Haplorhini suborders while anthropoids belong to the suborder Haplorhini. 

Classification – Infraorders 

Prosimians belong to the four infraorders: Tarsiiformes, Omomyiformes, Adapiformes, and Lemuriformes while anthropoids belong to the infraorder Simiiformes. 

Examples 

Prosimians include the bushbabies of Africa, the lemurs of Madagascar, and the lorises, pottos, and tarsiers of Southeast Asia while anthropoids include New World monkeys, Old World monkeys, apes, and humans. 

Time of Evolution 

While prosimians appeared around 55 million years ago, anthropoids appeared around 35 million years ago. 

Degree of Evolution 

Prosimians are relatively lower primates while anthropoids are higher primates. 

Habitat 

Furthermore, prosimians are mainly arboreal while anthropoids can be either arboreal or terrestrial.   

Characteristics 

Prosimians have a long face with a moist snout, prominent whiskers, large mobile ears, and large, slightly sideways-facing eyes while anthropoids have a relatively flat face, dry nose, small immobile ears, and forward-facing eyes.  

Brain Size 

In addition, prosimians have relatively small brain sizes while anthropoids have large brains. 

Skull 

Prosimians have no plate separating orbit from temporal fossa while anthropoids have a plate separating orbit from temporal fossa.  

Toothcomb 

Moreover, prosimians have lower incisors forming a toothcomb while anthropoids do not have a toothcomb.   

Rely on Senses 

Whereas prosimians mainly rely on the smell, anthropoids mainly rely on vision. 

Production of Vitamin C 

Non-tarsier prosimians are capable of producing vitamin C in their body while anthropoids are unable to producing vitamin C. 

Active Period 

Prosimians are nocturnal while anthropoids are diurnal. 

Conclusion 

Prosimians are the relatively primitive group of primates characterized by the presence of a long face, moist snout, and large, slightly sideways-facing eyes. They use toothcomb and rely on smell rather than vision as in higher primates. In addition, they have relatively small brains. Prosimians such as bushbabies, lemurs, lorises, pottos, and tarsiers are nocturnal. In comparison, anthropoids are the higher primates characterized by the presence of a flat face, dry nose, and forward-facing eyes. They have large brains and are active during the day time. Also, they tend to be more terrestrial than arboreal. Typically, anthropoids include New World monkeys, Old World monkeys, apes, and humans. Therefore, the main difference between prosimians and anthropoids is their characteristics and behavior. 

References:

1. “The Evolution of Primates | Biology II.” Lumen, Available Here.

Image Courtesy:

1. “Brown Lemur in Andasibe” By David Dennis – originally posted to Flickr as Brown Lemur in Andasibe (CC BY-SA 2.0) via Commons Wikimedia   
2. “Old & New World monkey faces” (CC BY 2.0) via Commons Wikimedia