Fossil Friday: Eurotamandua — Anteater or Not Even Close?
A very well-preserved fossil mammal from the Middle Eocene Messel pit in Germany was discovered in 1974 and described by Storch (1981) as Eurotamandua joresi. Famous German vertebrate paleontologist Gerhard Storch considered the fossil not only as the oldest fossil anteater (about 47 million years old) but also as the first European representative of this mammal order. This was a true sensation for paleontologists and zoologists alike. The simple reason is that anteaters belong to the group Xenarthra, which includes sloths, armadillos, and anteaters, and is generally believed to have always been an endemic to the neotropical region.
Extensive Phylogenetic Studies
A pitched controversy about the biogeographic and evolutionary implications resulted, and speculations ran wild. Extensive phylogenetic studies either affirmed the attribution of Eurotamandua to neotropical Xenarthra (Storch & Habersetzer 1991, Szalay & Schrenk 1994, Höss et al. 1996, Branham & Gaudin 1997, Gaudin & Branham 1998) or challenged it as uncertain (Gaudin 1999), or placed it closer to Pholidota (pangolins) and its fossil relatives Palaeanodonta (Rose & Emry 1993, Shoshani et al. 1997, Rose 1999, Delsuc et al. 2001), or attributed it to a totally independent lineage called Afredentata (Szalay & Schrenk 1998). All these scientists came to very different conclusions, even though they all worked with the same single fossil and its published description.
Finally, a study by Gaudin et al. (2009) established Eurotamandua as a fossil pangolin, contrary to their own earlier study. This was also supported by the more recent phylogenetic analysis of Kondrashov & Agadjanian (2012). An interesting detail is that Xenarthra and Pholidota were classically considered as related toothless mammals (Edentata) based on morphological similarities, but were shown to be totally unrelated and far removed in the mammalian tree of life based on molecular data (Xenarthra at the very base of mammals or as sister group to Afrotheria, but Pholidota as closest relative to carnivorans deeply nested within Laurasiatheria).
Yet More Controversy
However, an attribution of Eurotamandua to pangolins did not prevent further controversy. Szalay & Schrenk (1998) considered the Messel pholidote Eomanis krebsi (attributed to Euromanis by Gaudin et al. 2009) as a juvenile Eurotamandua and thus as synonym of this taxon. This was strongly rejected by Horovitz et al. (2005) based on the leg morphology. By the way: the apparent typical xenarthran joints described by Storch (1981) as a crucial character could not be corroborated by other studies (Rose & Emry 1993, Szalay & Schrenk 1994, Gaudin 1999) and ultimately turned out to be mere artifacts of preparation and restoration of the fossil (Storch 2003). All the other unique anatomical similarities between Eurotamandua and anteaters, that were previously considered as unequivocal synapomorphies (Branham & Gaudin 1997), are now considered evolutionary convergences. These include quite complex features such as horizontal palatal plates and a supplementary bulla tympanica (Storch & Habersetzer 1991).
Darwinists thus have to appeal to the ad hoc hypothesis of convergent adaptation to similar lifestyles, which of course increases the problem of how a blind evolutionary search process could stumble upon the same complex solutions multiple times. A design perspective can explain such incongruent data much better than a Darwinian perspective, because intelligent designers typically reuse the same innovations and principles in different instantiations.
- Branham DG & Gaudin TJ 1997. The Phylogeny of the Myrmecophagidae (Mammalia, Xenarthra, Vermilingua) and the Relationships of Eurotamandua. Journal of Vertebrate Paleontology 17(Suppl. 3), 33A. DOI: https://doi.org/10.1080/02724634.1997.10011028.
- Delsuc F, Catzeflis FM, Stanhope MJ & Douzery EJP 2001. The evolution of armadillos, anteaters and sloths depicted by nuclear and mitochondrial phylogenies: implications for the status of the enigmatic fossil Eurotamandua. Proceedings of the Royal Society of London B 268, 1605–1615. DOI: https://doi.org/10.1098/rspb.2001.1702.
- Gaudin TJ 1999. The morphology of xenarthrous vertebrae (Mammalia: Xenarthra). Fieldiana: Geology NS 41, 1–38. DOI: https://doi.org/10.5962/bhl.title.5269.
- Gaudin TJ & Branham DG 1998. The Phylogeny of the Myrmecophagidae (Mammalia, Xenarthra, Vermilingua) and the Relationship of Eurotamandua to the Vermilingua. Journal of Mammalian Evolution 5(3), 237–265. DOI: https://doi.org/10.1023/A:1020512529767.
- Gaudin TJ, Emry RJ & Wible JR 2009. The Phylogeny of Living and Extinct Pangolins (Mammalia, Pholidota) and Associated Taxa: A Morphology Based Analysis. Journal of Mammal Evolution 16, 235–305. DOI: https://doi.org/10.1007/s10914-009-9119-9.
- Höss M, Dilling A, Currant A & Pääbo S 1996. Molecular phylogeny of the extinct ground sloth Mylodon darwinii. PNAS 93(1), 181–185. DOI: https://doi.org/10.1073/pnas.93.1.181.
- Horovitz I, Storch G & Martin T 2005. Ankle structure in Eocene pholidotan mammal Eomanis krebsi and its taxonomic implications. Acta Palaeontologica Polonica 50(3), 545–548. https://www.app.pan.pl/article/item/app50-545.html
- Kondrashov P & Agadjanian AK 2012. A nearly complete skeleton of Ernanodon(Mammalia, Palaeanodonta) from Mongolia: morphofunctional analysis. Journal of Vertebrate Paleontology 32(5), 983–1001. DOI: https://doi.org/10.1080/02724634.2012.694319.
- Rose KD 1999. Eurotamandua and Palaeanodonta: convergent or related? Paläontologische Zeitschrift 73(3/4), 395–401. DOI: https://doi.org/10.1007/BF02988050.
- Rose KD & Emry RJ 1993. Relationships of Xenarthra, Pholidota, and fossil ‘Edentates’: the morphological evidence. pp. 81–102 in: Szalay FS, Novacek MJ & McKenna MC (eds). Mammal Phylogeny (Placentals). Springer, New York (NY).
- Shoshani J, McKenna MC, Rose KD & Emry RJ 1997. Eurotamandua is a pholidotan not a xenarthran. Journal of Vertebrate Paleontology 17(Suppl. 3), 76A. DOI: https://doi.org/10.1080/02724634.1997.10011028.
- Storch G 1981. Eurotamandua joresi, ein Myrmecophagide aus dem Eozän der “Grube Messel” bei Darmstadt (Mammalia, Xenarthra). Senckenbergiana lethaea 61(3/6), 247–289. https://www.schweizerbart.de/publications/detail/artno/190506103/Senckenbergiana_Lethaea_61_3_6
- Storch G 2003. Fossil Old World „edentates“ (Mammalia). Senckenbergiana biologica83(1), 51–60.
- Storch G & Habersetzer J 1991. Rückverlagerte Choanen und akzessorische Bulla typanica bei rezenten Vermilingua und Eurotamandua aus dem Eozän von Messel (Mammalia: Xenarthra). Zeitschrift für Säugetierkunde 56, 257–271. https://biostor.org/reference/183398
- Szalay FS & Schrenk F 1994. Middle Eocene Eurotamandua and the early differentiation of the Edentata. Journal of Vertebrate Paleontology 14(Suppl. 3), 48A. DOI: https://doi.org/10.1080/02724634.1994.10011592.
- Szalay FS & Schrenk F 1998. The Middle Eocene Eurotamandua and a Darwinian phylogenetic analysis. Kaupia – Darmstädter Beiträge zur Naturgeschichte 7, 97–186.