The Elephant Explosion
The title is not intended to suggest pieces of pachyderm flying all over the place, but rather one paleontologist’s theory about the rapid pace of elephant evolution 60 million years ago. He bases his ideas on a small fossil he found in Morocco. According to him, the primitive ancestor of all elephants (order Proboscidea) lived 5 million years earlier than thought, and gave rise to “one of the most spectacular examples of morphological evolution known in Mammalia” that occurred in “a rapid and basically explosive placental radiation.”
Emmanuel Gheerbrant, a paleontologist in Paris, described his fossil Eritherium azzouzorum in PNAS.1 His evolutionary story was picked up by Jeanna Bryner at Live Science who wrote about the “oldest elephant relative found.” Elephant? Bryner admitted, “the animal would not have looked much like an elephant. It was just 1.6 to 2 feet (50 to 60 cm) long and weighed 9 to 11 pounds (4 to 5 kg).” That’s compared to a modern elephant standing 11 feet tall at the shoulder and weighing 5 tons. New Scientist joined in, saying that “You wouldn’t have recognized Eritherium as an elephant when it was roaming Morocco 60 million years ago… But detailed study of the newly discovered fossil’s teeth, jaws and skull shows it to be the oldest member yet found of the order Proboscidea, of which elephants are the only living survivors.” New Scientist hoped that “The new find may shed light on the origins of elephants and other mammals… It shows elephants were making evolutionary progress 5 million years after the dinosaurs died out.”
Since pachyderms didn’t evolve till 34 million years ago, Darwin apparently shipped the trunk 26 million years late. How, then, could Gheerbrant call this an ancestor of the gentle giants we know and live in the local zoo? Bryner explained, “The animal’s relation to elephants was determined via analysis of the specimen’s teeth and skull. While it lacked a trunk, the animal had an enlarged first incisor, which researcher Emmanuel Gheerbrant of the National Museum of Natural History in Paris, France, says represents a primitive tusk.” It is doubtful that this little animal used a tooth enlarged by millimeters to pull down trees.
That word “primitive” was indeed found all over Gheerbrant’s paper (used 19 times). Yet for the animal itself, its features would have seemed well adapted for its own environment. Is not the word “primitive” a judgment call by the paleontologist assuming it was “making evolutionary progress” from primitive to advanced? That idea would be guilty of circular reasoning. Another kind of circularity was revealed in the dating of the fossil. The estimate of 60 million years was based entirely on index fossils and stratigraphy – both of which assume the evolutionary dating scheme the author was trying to use to establish the fossil’s time and place in evolutionary history.
A look through the scientific paper reveals other statements that cast doubt on the author’s confidence that this fossil has anything to do with the evolution of elephants. For one thing, the photo of the fossil pieces shows no postcranial anatomy. His judgment was made entirely on pieces of skull and jaw and five teeth. None of the teeth looks anything like a primitive tusk – nor did he claim so in the paper, regardless of what he told the press.
For another, placement of this fossil in a phylogenetic position with the Proboscidea involved numerous human judgment calls on his part. He had to juggle which pieces of evidence, based on tiny measurements from the fragmentary fossil, represent plesiomorphies (traits present before the common ancestor), synapomorphies (traits present in the common ancestor), and homoplasies (unrelated but similar traits attributed to “convergent evolution”). Of the latter, his table listed 11 homoplasies with other unrelated groups. The factors he considered worthy were then plugged into computer software that tried to build an evolutionary tree out of them. The outcome of tree-building software, however, can vary widely depending on the criteria inserted or left out, the relative weighting of factors, the algorithm used, and the outgroup selected (see 07/26/2008, 06/26/2008, 10/15/2003, and especially 10/01/2005 and 07/25/2002).
The following quotes reveal something of the contradictory data, the gaps in empirical data from fossils, and the juggling involved in reaching a conclusion. Notice how his best fit was obtained with his own previous work – raising additional questions about objectivity:
The TNT unweighted parsimony analysis including Eritherium yields a very poorly resolved consensus tree mainly resulting from the unstable position of Khamsaconus. Analysis without Khamsaconus shows that, besides the robust proboscidean relationships of Eritherium, basal relationships among paenungulates remain unstable, as illustrated by the basal polytomy in the consensus (Fig. 3A). This polytomy is basically related to our poor fossil knowledge of the ancestral morphotype of several orders such as Embrithopoda, Desmostylia, and Anthracobunia. Our analysis supports a Sirenia-Desmostylia clade sister group of Proboscidea within Tethytheria. The standard TNT “implied weighting” analysis yields a topology (Fig. 3B), which is nearly identical to that of Gheerbrant et al.
Here’s another quote that reveals multiple levels of subjectivity:2
The bunodont incipient lophodont morphotype is derived relative to the eutherian condition, and it is distinct from the perissodactyl pattern. This morphotype is an additional morphological character and one of the most remarkable dental characters reported for close relationships of paenungulates, macroscelideans, and louisinines. However, our parsimony analysis does not formally support sister-group relationships of the Macroscelidea plus Louisininae and the Paenungulata by contrast to molecular and recent morphological analyses advocating the Afrotheria clade. The recovered topology (Fig. 3) shows a sister-group relationship of Laurasian lophodont ungulates such as perissodactyls to paenungulates, instead of the macroscelideans (and louisinines). Similarly, our analysis does not discriminate clearly Laurasian (e.g., phenacodontids) and African (e.g., Ocepeia) “condylarths” as possible early ungulate representatives of molecular laurasiatherian and afrotherian clades. Fossils gaps, and especially for African taxa, most probably explain poorly resolved cladistic basal relationships of the Paenungulata in our tree (Fig. 3). These gaps are illustrated by our poor knowledge of the ancestral morphotype of several key paenungulates orders; for instance, the ancestral relative size of the last molar in paenungulates is challenged by Eritherium (M33 not enlarged). At lower level in the tree, the morphological and fossil gap is even worse for the phylogenetic analysis of the superordinal clade Afrotheria including Tenrecoidea and Tubulidentata, which are excluded from this study because of the lack of Paleogene data. In this respect, the cladistic study of Eritherium does not help to test the question of the macroscelidean position within Afrotheria. However, Eritherium dental morphology argues for a bunodont-lophodont, i.e., ungulatelike, ancestral morphotype for the Paenungulata, Louisininae, and Macroscelidea, within putative Afrotheria.
A lot of his evolutionary reasoning, therefore, depends on tiny measurements of tooth shape and systematic gaps in fossil evidence. The “ancestral morphotype” exists only in the evolutionist’s imagination.
Given these empirical problems, it does not appear even possible to arrive at a definitive evolutionary analysis from the fossil evidence. This creature could have been called one more well-adapted, extinct mammal, like many other well-adapted, extinct mammals, and left at that. The story of evolution, however, is what received prominence. Gheerbrant spoke of a “rapid paenungulate radiation at the Cretaceous-Tertiary (KT) transition” several times. In fact, it was this story line that excused the lack of evidence: “Rapid paenungulate radiation and fossil gaps may explain poorly resolved interordinal relationships,” he said at one point. The elephants-to-be must have been evolving so quickly they didn’t have time to leave any fossils. In fact, this rapid evolution involved more than the Proboscidea: there was a “rapid and basically explosive placental radiation,” he said. That explosion involved all the post-Cretaceous placental mammals.
So here is another explosion to add to the Cambrian explosion: a “basically explosive placental radiation” that was used to support evolutionary theory, as was the Cambrian explosion, by the lack of evidence for it (see 05/10/2008).
1. Emmanuel Gheerbrant, “Paleocene emergence of elephant relatives and the rapid radiation of African ungulates,” Proceedings of the National Academy of Sciences, print June 22, 2009, doi: 10.1073/pnas.0900251106.
2. Note: the reader does not need to understand the jargon to get a sense of the fudging that goes on. Curious readers can use Dictionary.com for definitions and the Reference.com page on cladistic analysis.
Day by day, we expose the unscientific divination practices of the Darwin sooth-slayers. Don’t be intimidated by the jargon. You can look it up. Learn to perceive the methods, omissions, assumptions and philosophy that makes these modern-day shamans pretend to be doing science, when they are really practicing divination to conjure up the Will of Darwin.