assignment biology darwinism masillae paper

assignment-biology-darwinism-masillae-paper

Description
Introduction: Darwinius masillae
The Discovery
On May 19, 2009, a team led by paleontologist Jørn Hurum of the Natural History Museum in Oslo Norway announced a significant new fossil discovery to the world. Nicknamed “Ida” after Hurum’s daughter, the team argued that the fossil was a type specimen, the individual fossil used to describe a species new to science (also called a holotype). The team named the new species Darwinius masillae, because the discovery was made in the 200th anniversary year of Charles Darwin’s birth.

Ida was not a typical fossil discovery. The specimen had actually been discovered by a private collector much earlier, in 1983, near Messel Germany. Her remains had been split into two separate slabs, which remained separate until 2000. The collector kept the main part (known as “Slab A”), while the second part (“Slab B”) was sold to the Wyoming Dinosaur Center in the United States. The two slabs are shown here:

THE FOSSIL
The parts of skeleton B that are outside of the dashed lines were fabricated so the fossil would look complete when it was displayed. This is normal for fossil casts (replicas) but is not normally done with real fossils unless they are relatively worthless. In spite of the Plate B fabrication, Ida is a remarkable and very important fossil for two reasons: how complete the specimen is and the fossil’s antiquity. With 95% of the skeleton, she represents one of the most complete fossils of her age ever found. Better preservation of a more complete fossil always gives scientists more information– so this is really important. Ida’s remains are so well preserved because of the way she became fossilized (her taphonomy). She was found near an ancient volcanic lake called a maar that was formed by an explosion when hot magma underneath the earth’s surface came in contact with a water table. The lake had no rivers feeding into it, so it had very little oxygen, which you may remember from our Explorations reading is a condition that creates exceptional preservation potential for fossils. She is so well preserved that her last meal (fruit) was preserved and fossilized in her gut. How old is Ida? She comes from the Eocene epoch (55-34 mya) and is dated to 47 million years old, meaning she existed early in primate evolution. Her fossil was dated by taking a core sample from the volcanic rocks in the Messel pit that formed the lake.

Ida is small, with her tail she measures about 23 inches (58 centimeters) long and her body is only 9 inches long and as you can see, her legs are longer than her arms, suggesting that leaping was a normal mode of locomotion for her. This hypothesis is based on analogy (comparison with the skeletal structures of living species). Likewise, comparison to living primates’ dentition supports the evidence from her stomach contents and suggests she was a frugivore. Her large eye orbits probably indicate a nocturnal life style. Scientists assigned her sex as female based on the fact that she had no baculum, the male penile bone found in primates (though not in humans), and other skeletal features. Several other important traits are also very clear: Ida has five digits on her hands and feet, long fingers and toes and nails instead of claws on all of her digits. Importantly, she has fully opposable thumbs and toes on her hands and feet. She also had unerupted molars pushing out her baby teeth, so she was a juvenile, perhaps about 9 months of age. Finally, her cause of death is unknown, but it is clear she has a broken wrist. One possible scenario is that her broken wrist prevented her from climbing in trees and being closer to the ground may have caused her to be exposed to gasses from the lake, which could have caused her to lose consciousness and drown.

assignment-biology darwinism masillae-paper

Ida’s Taxonomic Significance

Where does Ida belong in the early primate family tree? How does her discovery change our understanding of this period in evolutionary history? The discovery of Darwinius masillae has had important significance for our understanding of early primate evolution. In addition to analogy (comparison to living species), the fossil record is also interpreted using comparison to the existing fossil record. The first thing to do with a fossil discovery like Ida is to determine which living taxa she is affiliated with. Many of her characteristics support that Ida is a primate (her limb structure, skull features, dentition, grasping hands, opposable digits) and there is no scientific debate on this point.

Once her general placement in primates is secure, the next question is which living primates does she resembles most closely. Ida is missing several key characteristics that are found among living lemurs and lorises. For example, Ida lacks a dental comb and doesn’t have a grooming claw on her hands and feet– both of these are traits found in living lemur species, as you learned in the last module. She also has a shorter snout than living lemurs and a tarsus (an ankle bone– the bone that tarsiers get their name from) that appears more like haplorhines than lemurs or lorises. Along with her highly opposable thumbs (again, more associated with living monkeys), these traits have led some to interpret Ida as a potential ancestor for the living haplorhines. Ida’s discoverers argued that her fossil may represent a transition from more primitive strepsirrhine ancestors to the haplorhine lineage (Franzen et al 2009). Once a fossil discovery is published and interpreted by its discoverers, their claims are evaluated and responded to by scholars with relevant expertise. It is quite normal for discussion and debate to occur around taxonomic assignment of a new species, especially when a new species is monotypic (there is only a single specimen that assignment is based on).

assignment-biology-darwinism-masillae-paper

In a 2009 article coauthored with Hurum, Franzen et al argue that the ancient primate group adapiforms that many scholars identify as likely ancestral to living strepsirrhines, should instead be seen as a transitional group between haplorhines and strepsirrhines (Franzen et al 2009). Stony Brook University scholar Eric Seiffert and colleagues disagree with these interpretations,arguing that Franzen and his colleagues analyzed too few traits in their paper. Seffert and colleagues examined 360 morphological traits across 117 species of extant and extinct primates, and argue that Ida is more closely related to living lemurs and lorises, but should be put on a side branch, along with another recently discovered 37 mya primate, Afradapis (Seiffert et al 2009). According to Seiffert’s analysis, the similarities between Ida and living haplorhines are not because they are ancestral to them, but rather due to convergent evolution, where organisms not closely related evolve similar characteristics due to occupying similar environmental niches. This is a phylogenetic tree representing Seiffert’s interpretation:

Another critical assessment of Franzen et al was offered by Williams et al (2010), who also assert that Darwinius is better seen as basal (meaning a group that gave rise to a later lineage) to strepsirrhines and not haplorhines, as the discoverers claimed. Darwinius’ discoverer Jørn Hurum has said he is open to the possibility that Ida is on the strepsirrhine side of our primate family, but like so many taxonomic debates this one may never actually get resolved. Additional evidence is critical but given the ancient time frame, this evidence will be not be easy to come by and new discoveries, precious as they are, will no doubt complicate the picture further even as our understanding of the evolutionary past improves. Evolution is complicated and a better sample of fossils usually leads us in that direction!

assignment-biology-darwinism-masillae-paper

Sources
DARWINIUS. (N.D.). IN WIKIPEDIA. RETRIEVED MARCH 27, 2020. HTTPS://EN.WIKIPEDIA.ORG/WIKI/DARWINIUS (LINKS TO AN EXTERNAL SITE.)
Franzen, J. L.; Gingerich, P. D.; Habersetzer, J.; Hurum, J. H.; Von Koenigswald, W.; Smith, B. H. (2009). J., Hawks (ed.). Complete primate skeleton from the Middle Eocene of Messel in Germany: morphology and paleobiology (Links to an external site.). PLoS ONE. 4 (5): e5723.

Schons, Mary. 2011. Who Was Ida? October 24. National Geographic. https://www.nationalgeographic.org/article/who-was-ida/ (Links to an external site.)

Seiffert, Erik R.; Jonathan M. G. Perry; Elwyn L. Simons; Doug M. Boyer (22 October 2009). “Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates”. Nature. Nature Publishing Group. 461 (7267): 1118–1121. Bibcode (Links to an external site.):2009Natur.461.1118S. doi (Links to an external site.):10.1038/nature08429. PMID (Links to an external site.) 19847263.

Williams, Blythe A., Richard F. Kay, E. Christopher Kirk, and Callum F. Ross. 2010. Darwinius masillae Is a European Middle Eocene stem Strepsirrhine—a reply to Franzen et al. Journal of Human Evolution 59: 567–573.

Assignment
As you learned in your Explorations reading this week, fossils are historically the most important line of evidence about our distant past, but they can be extremely difficult to find. Important fossil discoveries like Ida still make headlines in magazines and newspapers for good reason. As the fossil record grows, so too does our understanding of the past and important new discoveries can rewrite our understanding of the evolutionary past.

For this assignment, you are to find an important fossil discovery that paleontologists or paleoanthropologists have made after the year 2000. Your fossil must be a hominin. Hominins are defined as species regarded as human, directly ancestral to humans, or very closely related to humans. Generally speaking, hominins are bipedal(walk on two legs). You can think of the story of Darwinius massilae above as a model for your assignment, though note that Darwiniius is not a hominin. I was also trying to illustrate some important concepts for this module, so you do not need to be quite as thorough as I was.

Start by googling important fossil discoveries and find one you think is interesting and important. Remember, your fossil must be a hominin and it must have been discovered since the year 2000. After you have chosen a fossil discovery, cover the following in a minimum of 800 words:

The fossil’s scientific name and popular name (if it has one)

A short account of the discovery (when, where, by whom, etc)

A description of the fossil remains, including the techniques used to date it

A photo of the fossil specimen(s)

A description of the important traits the fossil shows and their relationship to the fossil record and living species

AN ASSESSMENT OF THE IMPACT OF THE DISCOVERY ON OUR KNOWLEDGE OF EVOLUTION (INCLUDING DISCUSSION AND DEBATE ABOUT THE FOSSIL’S TAXONOMIC PLACE)
An image of a phylogeny/family tree showing where (at least some) scholars have placed your fossil discovery

A list of your sources (not included in the word total)

Important information for writing discussion questions and participation

Welcome to class

Hello class and welcome to the class and I will be your instructor for this course. This is a -week course and requires a lot of time commitment, organization, and a high level of dedication. Please use the class syllabus to guide you through all the assignments required for the course. I have also attached the classroom policies to this announcement to know your expectations for this course. Please review this document carefully and ask me any questions if you do. You could email me at any time or send me a message via the “message” icon in halo if you need to contact me. I check my email regularly, so you should get a response within 24 hours. If you have not heard from me within 24 hours and need to contact me urgently, please send a follow up text to

I strongly encourage that you do not wait until the very last minute to complete your assignments. Your assignments in weeks 4 and 5 require early planning as you would need to present a teaching plan and interview a community health provider. I advise you look at the requirements for these assignments at the beginning of the course and plan accordingly. I have posted the YouTube link that explains all the class assignments in detail. It is required that you watch this 32-minute video as the assignments from week 3 through 5 require that you follow the instructions to the letter to succeed. Failure to complete these assignments according to instructions might lead to a zero. After watching the video, please schedule a one-on-one with me to discuss your topic for your project by the second week of class. Use this link to schedule a 15-minute session. Please, call me at the time of your appointment on my number. Please note that I will NOT call you.

Please, be advised I do NOT accept any assignments by email. If you are having technical issues with uploading an assignment, contact the technical department and inform me of the issue. If you have any issues that would prevent you from getting your assignments to me by the deadline, please inform me to request a possible extension. Note that working fulltime or overtime is no excuse for late assignments. There is a 5%-point deduction for every day your assignment is late. This only applies to approved extensions. Late assignments will not be accepted.

If you think you would be needing accommodations due to any reasons, please contact the appropriate department to request accommodations.

Plagiarism is highly prohibited. Please ensure you are citing your sources correctly using APA 7th edition. All assignments including discussion posts should be formatted in APA with the appropriate spacing, font, margin, and indents. Any papers not well formatted would be returned back to you, hence, I advise you review APA formatting style. I have attached a sample paper in APA format and will also post sample discussion responses in subsequent announcements.

Your initial discussion post should be a minimum of 200 words and response posts should be a minimum of 150 words. Be advised that I grade based on quality and not necessarily the number of words you post. A minimum of TWO references should be used for your initial post. For your response post, you do not need references as personal experiences would count as response posts. If you however cite anything from the literature for your response post, it is required that you cite your reference. You should include a minimum of THREE references for papers in this course. Please note that references should be no more than 5 years old except recommended as a resource for the class. Furthermore, for each discussion board question, you need ONE initial substantive response and TWO substantive responses to either your classmates or your instructor for a total of THREE responses. There are TWO discussion questions each week, hence, you need a total minimum of SIX discussion posts for each week. I usually post a discussion question each week. You could also respond to these as it would count towards your required SIX discussion posts for the week.

I understand this is a lot of information to cover in 5 weeks, however, the Bible says in Philippians 4:13 that we can do all things through Christ that strengthens us. Even in times like this, we are encouraged by God’s word that we have that ability in us to succeed with His strength. I pray that each and every one of you receives strength for this course and life generally as we navigate through this pandemic that is shaking our world today. Relax and enjoy the course!

Hi Class,

Please read through the following information on writing a Discussion question response and participation posts.

Contact me if you have any questions.

Important information on Writing a Discussion Question

• Your response needs to be a minimum of 150 words (not including your list of references)
• There needs to be at least TWO references with ONE being a peer reviewed professional journal article.
• Include in-text citations in your response
• Do not include quotes—instead summarize and paraphrase the information
• Follow APA-7th edition
• Points will be deducted if the above is not followed

Participation –replies to your classmates or instructor

• A minimum of 6 responses per week, on at least 3 days of the week.
• Each response needs at least ONE reference with citations—best if it is a peer reviewed journal article
• Each response needs to be at least 75 words in length (does not include your list of references)
• Responses need to be substantive by bringing information to the discussion or further enhance the discussion. Responses of “I agree” or “great post” does not count for the word count.
• Follow APA 7th edition
• Points will be deducted if the above is not followed

• Remember to use and follow APA-7th edition for all weekly assignments, discussion questions, and participation points.
• Here are some helpful links
• The is a great resource