What is the Difference Between Platyrrhines and Catarrhines

The main difference between platyrrhines and catarrhines is that platyrrhines are a parvorder of simians that contains flat-nosed primates, including New World monkeys, whereas catarrhines are a parvorder of simians that contains hooked-nose primates including Old World monkeys, apes, and humans. Furthermore, 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, platyrrhines have a large body size in comparison to catarrhines. 

Platyrrhines and catarrhines are the two parvorders of the infraorder Simiiformes, consisting of anthropoids. Generally, they differ by their nose shape, tail, number of premolar teeth, thumb, and the ectotympanic bone (ear bone).

Key Areas Covered 

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

Key Terms 

Catarrhines, Nose, Platyrrhines, Primates, Simiiformes, Tail

Platyrrhines – Taxonomy, Characteristics, Classification 

Platyrrhines are one of the two parvorders of anthropoids of the infraorder Anthropodea. This parvorder includes New World monkeys, who originated 40 million years ago in South America. Generally, New World monkeys live in Mexico and Central and South America. There are five families of platyrrhines: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. These are ranked together as the Ceboidea, which is the only extant superfamily of the parvorder Platyrrhini. 

Figure 1: Old World (Common Chimpanzee) and New World (Red-Faced Spider Monkey) Monkey Faces

Furthermore, the main characteristic feature of platyrrhines is the presence of a flat nose with side-facing nostrils. New World monkeys in the family Atelidae are the only primates having a prehensile tail. In addition, the dental formula of platyrrhines consists of 2 incisors, 1 canine, 3 premolars, and 2 or 3 molars. The colour vision of New World monkeys is determined by a single gene on the X chromosome. Therefore, males and homozygous females have dichromatic vision while heterozygous females have trichromatic vision. Moreover, New World monkeys are small to medium-sized primates. 

Catarrhines – Taxonomy, Characteristics, Classification 

Catarrhines are the second parvorder of anthropoids of the infraorder Anthropodiea. It includes Old World monkeys, apes, and humans. Old World monkeys and apes split 25 million years ago. In addition, the superfamilies of catarrhines include Propliopithecoidea, Pliopithecoidea, Dendropithecoidea, Saadanioidea, Parapithecoidea, Cercopithecoidea, and Hominoidea. Moreover, the superfamily Hominoidea includes two families:  family Hylobatidae (lesser apes or gibbons) and family Hominidae (greater apes including orangutans, gorillas, chimpanzees, and humans).

Figure 2: Stumptail Monkeys (Macaca arctoides)

Moreover, the main characteristic feature of catarrhines is their downward-facing, narrow noses. Old World monkeys have shorter, non-grasping tails while apes lack tails. On the other hand, catarrhines have 2 premolars. However, they have trichromatic vision and opposable thumbs. Furthermore, catarrhines have comparatively large bodies with a high level of sexual dimorphism. They also live in social groups without forming pair bonds. 

Similarities Between Platyrrhines and Catarrhines 

• Platyrrhines and catarrhines are the two parvorders of the infraorder Simiiformes, which is more recently known as Anthropoidea. 
• Therefore, they are anthropoids with flat noses. 
• Moreover, anthropoids are one of the infraorder of the suborder Haplorhines.  
• They are adapted to live in the trees of tropical forests. 
• All extant anthropoids share 27 Alu-SINE markers, which are genetic markers called short interspersed elements (SINEs), offering strong evidence in support of both haplorhine and strepsirrhine monophyly by being excellent phylogenetic markers with an extraordinarily low probability of convergent evolution. However, five SINEs support haplorhine monophyly to the exclusion of Strepsirrhines and eight are shared among Strepsirrhines.  
• They have four limbs: a pair of legs and a pair of arms with the altered shoulder girdle. 
• Furthermore, their limbs are highly flexible with dexterous fingers. 
• Generally, they have large body sizes and their body is covered with short, dense hair, except for the face. 
• Additionally, they have flat faces with small ears. 
• However, they have highly developed eyes with visual acuity, colour vision and an excellent depth of perception.  
• Their orbits are relatively small, forward-facing, and convergent. They also have a bony lamina posterior to the orbit, completely separating the eyes from the chewing muscles in the temporal fossa.  
• In addition to these, they are intelligent, and their brains are relatively large and complex. 
• They are diurnal and are omnivores, consuming small invertebrates, fruits, and plants. 

Difference Between Platyrrhines and Catarrhines 

Definition 

Platyrrhines refer to the parvorder Platyrrhini, consisting of flat-nosed simians, having more flatter noses than those other simians, with sideways-facing nostrils, while catarrhines refer to the second parvorder, parvorder Catarrhini, consisting of simians with hooked noses with nostrils facing downward. 

Origin 

Platyrrhines originated in South America around 40 million years ago while catarrhines split into Old World monkeys and apes around 25 million years ago. 

Examples 

Moreover, platyrrhines include New World monkeys, while catarrhines include Old World monkeys, apes, and humans. 

Habitat 

Another difference between Platyrrhines and catarrhines is that platyrrhines are more arboreal while catarrhines are more terrestrial. 

Body Size 

While platyrrhines have comparatively small body sizes, catarrhines have large body sizes. 

Ectotympanic Bone 

In addition, platyrrhines lack an ectotympanic bone while the ectotympanic bone of catarrhines extends laterally to form a tubular external auditory meatus.  

Noses and Nostrils 

Furthermore, platyrrhines have flatter noses with nostrils facing sideways separated by a wide septum while catarrhines have hooked noses with nostrils facing downwards separated by a small septum. 

Dental Formula 

Platyrrhines have  2 incisors, 1 canine, 3 premolars, and 2 or 3 molars while catarrhines have  2 incisors, 1 canine, 2 premolars, and 3 molars.  

Opposable Thumbs 

Platyrrhines lack opposable thumbs while catarrhines have opposable thumbs. 

Tail 

Moreover, platyrrhines have prehensile tails that are flexible and long while Old World monkeys of catarrhines have the shorter, non-grasping tails and apes lack a tail. 

Trichromatic Vision 

Platyrrhines typically lack trichromatic vision except for howler monkeys while catarrhines have trichromatic vision. 

Diet 

Platyrrhines are fewer folivores while catarrhines are more folivores. 

Behavior 

While platyrrhines form monogamous pair bonds and show substantial paternal care of young, catarrhines do not form monogamous pair bonds and do not show substantial paternal care of young. 

Conclusion 

Platyrrhines are one of the two parvorders of anthropoids, including New World monkeys. Moreover, this parvorder contains primates with flatter noses and their nostrils are facing sideways. In addition to these, the main significant features of Platyrrhines include their prehensile tail, three premolar teeth in each quadrant, wide nasal septum, a thumb that is not opposable, and the absence of an ectotympanic bone. Catarrhines are the second parvorder of anthropoids, including Old World monkeys, apes, and humans. However, these primates have hooked noses with downward-facing nostrils. Moreover, the other characteristic features of catarrhines include two premolar teeth in each quadrant, short tail in Old World monkeys and no tail in apes, narrow nasal septum, opposable thumb, and the presence of a tubular ectotympanic bone. Therefore, the main difference between Platyrrhines and catarrhines is their nose shape, tail, number of premolar teeth, thumb, and the ectotympanic bone.   

References:

1. Williams, B. A., et al. “New Perspectives on Anthropoid Origins.” Proceedings of the National Academy of Sciences, vol. 107, no. 11, Aug. 2010, pp. 4797–4804., doi:10.1073/pnas.0908320107.
2. The Old World Monkeys, Available Here.
3. Emilyzipko. “New World VS Old World Monkeys Notes.” Course Hero, Available Here.

Image Courtesy:

1. “Old & New World monkey faces” By cc-by-sa-4.0 (CC BY 2.0) via Commons Wikimedia   
2. “Macaca arctoides” By (Photograph by Frans de Waal, used with permission.) (CC BY 2.5) via Commons Wikimedia