8.1: Fossil Primates

Fossil Primates

Format: In-person or online

Author: Beth Shook

Modified from labs by McHenry, Henry M., University of California, Davis.

Time needed: 60 minutes

Supplies Needed

• Primate fossil replicas or 3D images of: Aegyptopithecus, Proconsul, Sivapithecus, and Gigantopithecus
• Extant primate skulls (real or casts) or 3D images of extant primate skulls
• Handouts or websites with information about plesiadapis, omomyids, adapids

Readings

• Perry, Jonathan and Stephanie Canington. 2019. Chapter 8: Primate Evolution. Explorations.

Introduction

This lab covers primate evolution from the Paleocene through the Miocene, with an emphasis on the Miocene apes.

• Station 1: The Paleocene (covers Plesiadapiforms)
• Station 2: The Eocene & first true primates (Omomyids and Adapids)
• Station 3: Oligocene (covers Aegyptopithecus)
• Station 4: Miocene & Proconsul
• Station 5: Miocene & Sivapithecus
• Station 6: Miocene & Gigantopithecus

Steps

• Before beginning this lab, the instructor should select skeletal materials, casts, or images of skeletal materials for students, and arrange them at various stations. All skeletal materials should be labeled with cards/small labels with terms that match the student worksheets (e.g. Primate, Strepsirrhine). At some stations a handout, website, or textbook passage will need to be provided to give students the information to answer the questions. Alternatively, virtual images can be linked to the student worksheet to create a virtual lab.
• Specific materials needed are:
  • Station 1: handout, website, or textbook passage containing information about the characteristics of Plesiadapiforms.
  • Station 2: handout, website, or textbook passage containing information about the characteristics omomyids and adapids shared with primates.
  • Station 3: (a) strepsirrhine (e.g. lemur) skull, (b) Old World monkey skull, (c) ape skull, (d) aegyptopithecus skull, and (e) images of these primates or primate skeletons to allow comparison between their forelimb and hindlimb length. Extant primate skulls should allow visibility of molar cusp patterns.
  • Station 4: (a) monkey skull, (b) ape skull, (c) human skull, and (d) proconsul skull. Extant primate skulls should allow visibility of molar cusp patterns.
  • Station 5: (a) African ape skull, (b) orangutan skull, and (c) Sivapithecus skull.
  • Station 6: (a) Gigantopithecus teeth and/or jaw, (b) Gorilla skull, and (c) human skull

• The instructor should choose to assign this lab as an individual or small group activity.
• An introduction to encourage students to think about the “big picture” events from each time period is helpful. Instructors should be sure students are familiar with the traits in the lab (e.g. dental arcade, Y5 or bilophodont molar cusp patterns) or are given resources to identify these traits at the various stations.
• The lab consists of six “stations.” Stations can be completed in any order, however there is a “Miocene” phylogeny that requires the completion of stations four through six first.
  • Station 1: Using the resources provided by the instructor, students compare plesiadapiforms and primates.
  • Station 2: Using images provided of omomyids and adapids, students complete the yes/no table on the Worksheet.
  • Station 3: Given the scenario described on the worksheet, and observation of Aegyptopithecus fossils or images, students complete the table.
  • Station 4-6: Students examine fossils from the Miocene (Proconsul, Sivapithecus, and Gigantopithecus) in order to complete the Worksheet questions.

Conclusion

• Instructors should have students report to the class on their answers for some/all of the stations. For example, each group could complete a small table for one station on the board. While some parts of the tables are more open ended, there are some traits that instructors will want to be sure students identified correctly.
• Instructors should connect the fossils with what we know of the primate phylogeny. For example, traits shared among most/all primates are seen in the earliest fossils.
• Specifically, the primate phylogeny that goes with Stations 4-6 should be covered during the wrap-up. Students can hypothesize, based on the lab, where they would put these fossils. Instructors can then discuss the locations that primatologists are placing them - recognizing that there is not always agreement.

Adapting for Online Learning

1 Not adaptable 2 Possible to adapt 3 Easy to adapt

This lab can be adapted by utilizing 3-D images of extant primates and primate fossils available at such sites as Sketchfab https://sketchfab.com/ (all the fossils and extant primates utilized in this lab), eSkeletons http://www.eskeletons.org/ (all extant primates in this lab), and/or African Fossils https://africanfossils.org/ (some fossils and some extant primates in this lab).

Morphosource https://www.morphosource.org/ by Duke University also has a collection of 3-D fossil images.

For Further Exploration

Dunsworth, Holly. 2015. How to Become a Primate Fossil. Nature Education Knowledge 6(7):1 https://www.nature.com/scitable/knowledge/library/how-to-become-a-primate-fossil-135630567/

Slicox, Mary T. 2014. Primate Origins and the Plesiadapiforms. Nature Education Knowledge 5(3):1 https://www.nature.com/scitable/knowledge/library/primate-origins-and-the-plesiadapiforms-106236783/

Talking Science. 2016. Gaga for Gigantopithecus. https://www.youtube.com/watch?v=mzhbvZB7e7Y

References

Perry, Jonathan and Stephanie Canington. 2019. “Chapter 8: Primate Evolution.” Explorations: An Open Invitation to Biological Anthropology, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association. http://explorations.americananthro.org/

Image Attributions

Anaptomorphus-descent-primates by Hubrecht A.A.W. The descent of the primates. Lectures delivered on the occasion of the sesquicentennial celebration of Princeton University. New York: Charles Scribner’s Sons, 1897, is in the Public Domain.

Plesiadapis tricuspidens by Nobu Tamura (Spinops) is under a CC BY-NC-ND 3.0 License.

Anaptomorphus, Life restoration of Tetonius homunculus (an omomyid) by W.B. Scott in A History of Land Mammals in the Western Hemisphere. New York: The Macmillan Company, is in the Public Domain.

Fossil Primates

Station 1: The Paleocene (Approximately 65 - 54 MYA): Primate-Like Mammals

Below is a reconstruction of Plesiadapis. These small quadrupeds came in many diverse forms, and represent part of the mammalian radiation that occurred in the Paleocene. They may be relatives of primates (a side branch), or some of them were perhaps even ancestral to primates as some of them have the auditory bulla, which contains the middle ear and is distinctive of primates.

Plesiadapis tricuspidens by Nobu Tamura (Spinops) is under a CC BY-NC-ND 3.0 License.

Plesiadapiforms lived in western North America, western Europe, Asia, and Africa at the start of the Paleocene. While at the right time to be early primates, they lack true primate characteristics.

Using the resources provided for you, what are four differences between plesiadapiforms and primates?

Station 2: The Eocene (Approximately 55 - 34 MYA): The First True Primates

In the Eocene, there were two early primate groups represented by the fossil record: omomyids and adapids.

The skull of Anaptomorphus (an omomyid). Hubrecht A.A.W. The descent of the primates. Lectures delivered on the occasion of the sesquicentennial celebration of Princeton University. New York: Charles Scribner’s Sons, 1897. U.S. Public Domain.

Life restoration of Tetonius homunculus (an omomyid) from W.B. Scott's (1858–1947). A History of Land Mammals in the Western Hemisphere. New York: The Macmillan Company. U.S. Public Domain.

Examine the pictures above, and the provided resources, to determine which of the following traits omomyids and adapids have that indicate they are primates. Please mark “yes” if at least one of the above primates exhibits the trait.

Shared with Primates	Yes or No?
Partially or fully enclosed eye orbits?
Eyes that are convergent (look forward)?
Small incisors and large canines?
Short snout?
Increased brain size?
Grasping hands?

Station 3: The Oligocene (Approximately 34 - 24 MYA): An Adaptive Radiation of Anthropoids

In the Oligocene, tropical rain forests extended far into areas that are now temperate zones. One of the best Oligocene fossil deposits is in the Egyptian desert—at a place called the Fayum. At one time this was an ideal habitat for anthropoid primates; a sluggish river delta surrounded by lush forest provided niches for several primate species.

In the 1960’s Dr. Elwyn Simons and a Yale expedition discovered a nearly complete skull of Aegyptopithecus. Simons maintained that Aegyptopithecus was the earliest ape, a member of the superfamily Hominoidea. Today most dispute this assertion and argue that Aegyptopithecus has a mosaic of features suggesting it was probably a primitive catarrhine. Compare the provided strepsirrhine, monkey, and ape skulls to Aegyptopithecus.

	Strepsirrhine	Old World Monkey	Ape	Aegyptopithecus
Eye orbit size & orientation
Brain size
Snout length (compared to cranial size)
Lower molar cusp pattern (Y5 or bilophodont)	N/A
Front to hind limb ratio				Equal length suggesting a slow arboreal quadruped

Which traits might Simons have regarded as hominoid (ape & human) like?

We now know that the ancestor of apes and Old World monkeys had the Y-5 molar cusp pattern. For the hominoid (ape & human) clade, then, is Y-5 a derived trait or primitive trait?

Station 4: The Miocene: Proconsul

Proconsul is well known from Early Middle Miocene sites (22-17 mya) in East Africa. Examine the teeth and jaws of Proconsul.

	Monkey	Ape	Human	Proconsul
Lower molar cusp pattern (Y5 or bilophodont)
Shape of dental arcade
Canine size

In its teeth and jaws, does Proconsul resemble an ape, a monkey, or human?

As ape-like as the jaws and teeth appear to be, the postcrania (skeleton) is very monkey-like. Detailed studies of the forelimb of Proconsul have shown that it lacked the brachiation ability present in living hominoid elbows and wrists. This is evidence that the common ancestor of living hominoids (gibbons, great apes, and humans) appeared after Proconsul.

Station 5: The Miocene: Sivapithecus

Sivapithecus lived in Asia between 12 and 8 MYA.

	An African Ape	Orangutan	Sivapithecus
Draw the overall shape of skull when viewed from side
Eye orbit shape
Closeness of eyes

There are a lot of similarities between Sivapithecus and orangutans of today! There are some differences, though, including differences in their arm bones. Sivapithecus was probably closely related to, but perhaps not directly ancestral to, orangutans.

Station 6: The Miocene: Gigantopithecus

Gigantopithecus, which means “giant ape”, has been found in China, India, and Vietnam, dating as far back as 8 MYA, but as recent as 500,000 YA.

Compare Gigantopithecus teeth and jaw to a Gorilla and a human. What similarities do you see? What differences do you see?

What type of diet do you think Gigantopithecus subsisted on? Why do you think that?

Station 4 - 6: The Miocene (Approximately 24 - 5 MYA): An Radiation of Apes

The Miocene was warmer and wetter than the present period. Apes were found in relative abundance in Africa and Eurasia in the Miocene. Proconsul was among the earliest (in Africa), and after Proconsul the apes spread and diversified: Dryopithecus in Europe, Sivapithecus and Gigantopithecus in Asia.

When you have finished looking at all of the fossils from the Miocene:

1) Draw a circle around the hominoid clade, and

2) After completing stations 4-6, mark where you think the fossil primates Proconsul, Sivapithecus, and Gigantopithecus best fit. Note: because they are fossils, they do not need to be listed at the top with the other primates, but can be drawn onto any lineage or as a side branch. Aegyptopithecus is drawn in as an example.