As part of the TBI Field School students get to work on new fossil material. Well, maybe not “new” in the normal sense of that word, but they get to work with material that no one else has laid hands on or thought about because it just came out of the ground a few days ago.
Dr. Fortelius’s research focuses on using fossils, especially teeth, to tell us about changing climates and environments through the chaotic Cenozoic and the methods he taught in lecture and lab generated student insights into the material.
Armed with new fossils and new techniques, several students saw the fossils collected at Lothagam and at Kangatotha as a chance to answer their own questions as part of independent student research projects that were presented at the end of the paleontology module. These aren’t simple student reports. This is real science.
Eve and Bailie examined the shape and size of the teeth collected at Lothagam and Kangatotha to reconstruct the climate and precipitation at the two sites. Dr. Fortelius has been doing these reconstructions in Eurasia for many years, but has a more limited sample of African localities. He’s working on building his African database and Eve and Bailie’s work directly contributed to the broader understanding of Africa’s rapidly changing climate over the last six million years.
Even and Bailie found the dental diversity at Lothagam was consistent with a tropical grassland environment, a result other workers had suggested based on the fossils recovered from the site. They also used the few animal dental remains recovered from Kangatotha to propose the first climatic reconstruction of the newly worked locality. They found the dental remains consistent with the temperature and precipitation of a shrubby desert. The fragments of human remains recovered from Kangatotha now had an environment to move through. But who were those people?
John and Cory decided to tackle that question. They examined the two skull fragments we collected at Kangatotha and included the mystery hominins in a cladistic analysis, a method of establishing the closest relatives of specimens by scoring them for a list of traits. They used a character list provided by researchers who study human evolution, Dr. Fred Grine and Dr. Heather Smith, and added their own new characters. They also performed a morphometric analysis, comparing the shapes of the skull fragments to the skulls of other extinct and living hominins. Their preliminary analysis suggests the Kangatotha skull fragments were not from fully modern humans, pushing the age of the site way past the Holocene age we originally thought we were working with when we first set boots on the ground north of the Turkwel.
Maegan and Rachel also worked with a Kangatotha mystery. On the last day in the last hour at the site, Maegan found a fragment of a sacrum, the bone that sits at the base of your vertebral column and forms the keystone of the pelvis.
In the field we made a tentative identification of the element as a human sacrum, but the ID didn’t sit right with Maegan and Rachel who set out to figure out who the sacrum belonged to with the limited comparative sample available at TBI. They tracked down images of extinct human sacra and looked at the hips of a chimp, camel, baboon, and cat. Nothing seemed like the perfect fit.
After some inconclusive measurements, they noted the similarities between the small cat sacrum and the large fossil. After spending some time with osteology books on African mammals they discovered the “hominid” sacrum of Kangatotha likely belonged to a big cat like a lion or maybe even a sabre-toothed cat. This was a very old-school paleontological analysis based on careful observations and comparisons with other bones. Sometimes there’s no school like the old school.
Ingrid and Natalie were also able to draw on the material collected at Lothagam in their analysis of body size reconstructions. As Dr. Fortelius pointed out several times in lecture, body size is the single most important factor when a paleontologist or biologist is trying to sort out the lifestyle of an animal. Body size and mass are directly related to metabolism, diet, reproduction, and locomotion. Over the years, paleontologists have tried to use every scrap of preserved bone to reconstruct the body sizes of ancient animals. Some are more accurate that others, and Ingrid and Natalie tried to figure out which gave the best estimates and what range of estimates were reconstructed by different equations. They then applied their reconstruction methods to the material collected at Lothagam and found a reconstructed range of body sizes for the hippos and bovids we collected only a few days earlier.
Ana was also interested in reconstructing body size, but chose to focus on vertebrae, an important part of an animal’s structure that has received very little attention from paleontolgists interested in body size, partially because complete vertebrae don’t preserve very well. However, Ana did find it was possible to estimate body mass accurately based on several linear measurements of different parts of a mammal’s backbone.
The next group of students were interested in using the methods developed by Dr. Fortelius to reconstruct diet based on the shape and wear of teeth. Meg and Sam used samples of modern goat teeth collected around TBI to figure out if their teeth recorded the actual diets of the browsing and grazing domestic stock. Their analysis worked beautifully. They found the goat’s teeth recorded a mixed feeding population and the goats of South Turkwel had diet comparable to browsing/grazing siaga antelope and hyraxes.
Aaron and Rosie focused on the reasons for the wear observed by Sam and Meg by collecting plants from around the compound, the river, the road, and nearby clearings. They wanted to know how much grit and dust is carried by plants consumed by goats. After several attempts to get dust strained from foliage, they finally discovered Indigofera, the ubiquitous spikey shrubs that the goats enthusiastically graze, also carries a lot of dust making it tough to figure out if the wear on the goat teeth observed by Meg and Sam is related to inorganic grit or the organic, gritty properties of the plants the goats munch.
Marcel was also drawn in to goat tooth questions because of the sheer abundance of the things. Every time we go to the soccer pitch, we collect anther half dozen jaws and skull fragments to add to the comparative collection that is growing in the South Turkwel collection. If you know anyone searching for a population of desert goats to study, refer them here.
Marcel wanted to see if he could establish a new measurement for reconstructing diet. He settled on the slope of dental wear and found – after a long time collecting angle measurement from molars – a decent correlation between diet and slope.
After so much discussion of teeth and body size, Francis wanted to figure out the connection between the two. He wanted to examine dental variation in extinct horses found in the Turkana Basin. After a lot of number crunching and regressions he found there were distinct differences in both aspects of the skeleton in the horses that proceeded the zebras we see in East Africa today.
Holly’s dental project used teeth as proxies for reconstructing climate fluctuations in the Turkana Basin. She used a database Dr. Meave Leakey and Dr. Fortelius have been collaborating on to reconstruct the spikes in temperature and humidity also found in the isotopic record.
Leanna opted to use the systematic techniques introduced during the vertebrate paleontology to score and categorize a really weird group of organism: us! She designed a series of questions that she asked each student and TA then translated her results into a character list like a paleontologist studying variation in the skeletons of different animals. Her phylogenetic tree then clumped students based on shared traits both biological (shoe size) and personal (do you have a tattoo?). Suffice it to say, the results made everyone smile. And we learned about cladistics to boot.
Tim and Ashley wanted to take the same cladistic systematic techniques usually reserved for biological questions and apply them to the archaeological record to see if known cultural connections between groups would clump the way related animals clump.
Ashley took her interest in boats to a new level by digging through the available literature on the boats of the Turkana Basin and the Nile River Valley to reconstruct a phylogeny that echoed the known cultural exchange through East Africa. Tim had less luck getting harpoon points to track their known temporal and geographic ranges, but he now has the analytical tools to tackle other relationships in the archaeological record.
After hours of research and analysis, the students presented their results to one another. The presentations were fantastic. Many could easily have been presented at a professional meeting after a little more time for data collection.
For the final, each student sat with Dr. Fortelius and an assortment of fossils. They were asked to identify the material and speculate on the biology of the fossilized material, an ability few students had before the module began. Most handled the task effortlessly and only needed a few nudges in the right direction to make a successful identification. Now that we had an understanding of the environment that surrounded our earliest ancestors, it was time to turn our full attention to the apes that opted to walk on two legs and started the fascinating lineage that meandered its way to us…