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Fossil Friday: Miocene Aardvarks and the Abrupt Origin of Tubulidentata 

 Günter Bechly 

This Fossil Friday we continue our series on the origins of placental mammal orders with the aardvark order Tubulidentata. Aardvarks are a strange group of insectivorous mammals with a single living relic species Orycteropus afer, which is endemic to subsaharan Africa and exclusively feeds on ants and termites. The order is named after the characteristic tube-shaped teeth that lack enamel. Aardvarks are often considered to be living fossils (Bennett 2017, Shoshani 2021, Anonymous 2022). So, what about their actual fossil history? Including the living species there were 5 genera and 17 valid species described in the order Tubulidentata (Lehmann 2009, Pickford 2019), but generally their fossil record is comparatively sparse until this day (Koufos 2022). 

Miocene to Pleistocene 

Fossil aardvark species have been described from the Miocene to Pleistocene of Africa, southern Europe, and South Asia (Patterson 1975, Lehmann 2006, 2009, Asher & Seiffert 2010). Until recently the oldest undisputed fossil aardvarks were the two species Orycteropus minutus and Myorycteropus africanus from Lower Miocene deposits in Kenya (MacInnes 1956, Patterson 1975, Pickford 1975, Lehmann 2006), which were dated to an age of 19.6 mya and 17.8 mya respectively (Lehmann 2007). Slightly older undescribed remains were mentioned by Pickford & Andrews (1981). Pickford (2019) described the new fossil aardvark genus Eteketoni from the Lower Miocene of Uganda, which may be closely related to Myorycteropus and now rivals Orycteropus afrianus as oldest fossil record of the order with an estimated age of 20-18.5 mya.

McKenna & Bell (1997) mentioned the two genera Archaeorycteropus and Palaeorycteropus from the Oligocene of Quercy in France (ca. 34 mya) as questionable tubulidentates, which would qualify as oldest fossil record of the order. Pickford (1975) had at least Palaeorycteropus listed as fossil Tubulidentata, and Shoshani (2001) also accepted this genus as Oligocene record of Tubulidentata. However, several earlier works had already strongly disputed that either of these two genera is a tubulidentate at all (Simpson 1931, Thenius & Hofer 1960, Patterson 1975, Thewissen 1985). Lehmann (2007, 2009) agreed that both genera are Eutheria of uncertain relationship. Therefore, Asher & Seiffert (2010) excluded both from their phylogenetic tree of Afrotheria. 

Leptomanis edwardsi is another enigmatic fossil mammal from the Oligocene of Quercy, and was mostly regarded as a putative relative of pangolins. Simpson (1931) thought that it is “possibly an orycteropodid” but put this with a question mark. Thewissen (1985) re-described the material of Leptomanis and concluded that “the best option for Leptomanis seems to be that it is the oldest tubulidentate so far known.” Others remained unconvinced and considered Leptomanis to be of uncertain affinities (Patterson 1975, 1978, Lehmann 2007, 2009). Gaudin et al. (2009) listed Leptomanis as a synonym of Necromanis within the order Pholidota, thus as a fossil pangolin. Finally, Crochet et al. (2015) disputed the synonymy with Necromanis but affirmed the position in Pholidota.

It has been suggested by some experts that an extinct order of carnivorous African mammals called Ptolemaiida might be related to aardvarks (Simons & Gingerich 1974, Nishihara et al. 2005, Cote et al. 2007, Seiffert 2007). The most primitive but not the oldest member of Ptolemaiida is the enigmatic species Kelba quadeemae from the Early Miocene of East Africa about 18.3 mya (Savage 1965, Cote et al. 2007). The oldest fossil record of Ptolemaiida is material from the latest Eocene of Fayum in Egypt (Simons & Bown 1995), which therefore could also be the oldest putative stem group representatives of Tubulidentata. However, this relationship is far from established. 

The Eocene 

genera Herodotius and Chambius, which were previously considered as stem macroscelideans, never clustered with Macroscelidea but were recovered as sister group of aardvarks in some of the trees by Seiffert (2007), which would put the oldest fossil record of tubulidentate lineage into the Eocene as well. However, this result was unstable and in some other trees of the same author these herodotiine genera rather clustered with pseudoungulates, paenungulates, or hyraxes. 

A Real Conundrum 

So, we are left with a real conundrum for Darwinists. On the one hand, Shoshani (2001) concluded about Tubulidentata: 

Little evolution has taken place in the genus over almost 20 million years, this is a hallmark of living fossils … , in all probability, the origin of tubulidentate taxa might date to the beginning of the Cenozoic era (Palaeocene epoch, about 65 Ma), and perhaps earlier (in the Cretaceous epoch of the Mesozoic era, some 70 Ma). 

On the other hand aardvarks and their fossil relatives only appear much later in the fossil record of the Miocene less than 20 million years ago. Indeed, they represent the youngest of the placental mammal orders and one of the very few exceptions that are not first recorded in a narrow window of time in the Paleocene/Eocene (also see Asher & Seiffert 2010: fig. 46.1).

It is also interesting to note that aardvarks were long believed to be closely related to the Xenarthra and Pholidota (pangolins) within a hypothetical group Edentata. Rare dissenters like Le Gros Clark & Sonntag (1926) were vindicated by modern phylogenomic studies, which demonstrated that all three orders are unrelated and aardvarks belong to the African mammal clade Afrotheria (Asher & Seiffert 2010), which is hardly supported by any anatomical similarities. So much about the congruence of anatomical and genetic similarity predicted by Darwin’s theory.

Next Fossil Friday we will look into another member of the Afrotheria, i.e., the order Macroscelidea that includes the uber cute elephant shrews. 

References 

Anonymous 2022. Dead Pig Walking: Aardvarks, “Living Fossils” in the Bush. Thomson Safaris. https://thomsonsafaris.com/blog/aardvarks-living-fossils/

Asher RJ & Seiffert ER 2010. Systematics of Endemic African Mammals. Chapter 46, pp. 911–928 in: Werdelin L & Sanders WJ (eds). Cenozoic Mammals of Africa. University of California Press, Berkeley (CA), 1008 pp. https://doi.org/10.1525/california/9780520257214.003.0046

Bennett DJ 2017. An Appraisal of the ‘Living Fossil’ Concept. Unpublished Ph.D. thesis, Imperial College, London (UK), xi+251 pp. https://spiral.imperial.ac.uk/bitstream/10044/1/68534/1/Bennett-D-2017-PhD-Thesis.pdf

Cote S, Werdelin L, Seiffert ER & Barry JC 2007. Additional material of the enigmatic Early Miocene mammal Kelba and its relationship to the order Ptolemaiida. PNAS 104(13), 5510–5515. DOI: https://doi.org/10.1073/pnas.0700441104

Crochet J-Y, Hautier L & Lehmann T 2015. A pangolin (Manidae, Pholidota, Mammalia) from the French Quercy phosphorites (Pech du Fraysse, Saint-Projet, Tarn-et-Garonne, late Oligocene, MP 28). Palaeovertebrata 39(2):e4, 1–8. DOI: https://doi.org/10.18563/pv.39.2.e4

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 Mammalian Evolution 16, 235–305. DOI: https://doi.org/10.1007/s10914-009-9119-9 

Koufos GD 2022. The Fossil Record of Aardvarks (Mammalia: Tubulidentata: Orycteropodidae) in Greece. pp. 283–290 in: Vlachos E (ed.). Fossil Vertebrates of Greece Vol. 1. Springer, Cham (CH), xxi+710 pp. DOI: https://doi.org/10.1007/978-3-030-68398-6_10

Le Gros Clark WE & Sonntag CF 1926. A monograph of Orycteropus afer. – III. The skull. The Skeleton of the Trunk and Limbs. Proceedings of the Zoological Society of London96(2), 445–485. DOI: https://doi.org/10.1111/j.1469-7998.1926.tb08108.x

Lehmann T 2006. Biodiversity of the Tubulidentata over Geological time. Afrotherian Conservation 4, 6–11. https://www.afrotheria.net/Afrotherian_Conservation_4.pdf

Lehmann T 2007. Amended taxonomy of the order Tubulidentata (Mammalia, Eutheria). Annals of the Transvaal Museum 44(1), 179–196. https://hdl.handle.net/10520/EJC83654

Lehmann T 2009. Phylogeny and systematics of the Orycteropodidae (Mammalia, Tubulidentata). Zoological Journal of the Linnean Society 155(3), 649–702. DOI: https://doi.org/10.1111/j.1096-3642.2008.00460.x

MacInnes DG 1956. Fossil Tubulidentata from East Africa. In: Fossil Mammals of Africa No. 10. British Museum (Natural History), London (UK), 38 pp. https://www.biodiversitylibrary.org/item/206520#page/5/mode/1up

McKenna MC & Bell SK 1997. Classification of mammals above the species level. Colombia University Press, New York, 631 pp.Nishihara H, Satta Y, Nikaido M, Thewissen JG, Stanhope MJ & Okada N 2005. A retroposon analysis of Afrotherian phylogeny. Molecular Biology and Evolution 22(9), 1823–1833. DOI: https://doi.org/10.1093/molbev/msi179

Patterson B 1975. The fossil aardvarks (Mammalia: Tubulidentata). Bulletin of the Museum of Comparative Zoology 147(5), 185–237. https://ia800200.us.archive.org/15/items/biostor-663/biostor-663.pdf

Patterson B 1978. Pholidota and Tubulidentata. Chapter 12, pp 268–278 in: Maglio VJ & Cooke HBS (eds). Evolution of African Mammals. Harvard University Press, Cambridge (MA), 641 pp. DOI: https://doi.org/10.4159/harvard.9780674431263.c13

Pickford M 1975. New fossil Orycteropodidae (Mammalia, Tubulidentata) from East Africa. Orycteropus minutus sp. nov. and Orycteropus chemeldoi sp. nov. Netherlands Journal of Zoology 25(1), 57–88. DOI: https://doi.org/10.1163/002829675X00137

Pickford M 2019. Orycteropodidae (Tubulidentata, Mammalia) from the Early Miocene of Napak, Uganda. Münchner Geowissenschaftliche Abhandlungen Reihe A 47, 1–101. https://pfeil-verlag.de/en/publications/orycteropodidae-tubulidentata-mammalia-from-the-early-miocene-of-napak-uganda/ 

Pickford M & Andrews P 1981. The Tinderet Miocene sequence in Kenya. Journal of Human Evolution 10(1), 11–33. DOI: https://doi.org/10.1016/S0047-2484(81)80023-1

Savage RJG 1965. Fossil Mammals of Africa No. 19: The Miocene Carnivora of East Africa. Bulletin of the British Museum (Natural History), Geology 10(8), 239–316. https://www.biodiversitylibrary.org/item/112052#page/384/mode/1up

Seiffert ER 2007. A new estimate of afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence. BMC Evolutionary Biology 7(1):224, 1–13. DOI: https://doi.org/10.1186/1471-2148-7-224

Shoshani J 2001. Tubulidentata (Aardvarks). Encyclopedia of Life Sciences Vol. 18. Nature Publishing Group, London (UK). DOI: https://doi.org/10.1038/npg.els.0001578

Simons EL & Bown TM 1995. Ptolemaiida, a new order of Mammalia–with description of the cranium of Ptolemaia grangeri. PNAS 92(8), 3269–3273. DOI: https://doi.org/10.1073/pnas.92.8.3269

Simons EL & Gingerich PD 1974. New carnivorous mammals from the Oligocene of Egypt. Annals of the Geological Survey of Egypt 4, 157–166. http://www-personal.umich.edu/~gingeric/PDFfiles/PDG015_Masrasector.pdf

Simpson GG 1931. Metacheiromys and the Edentata. Bulletin of the American Museum of Natural History 59, 295–381. http://hdl.handle.net/2246/346

Thenius E & Hofer H 1960. Stammesgeschichte der Säugetiere. Eine Übersicht über Tatsachen und Probleme der Evolution der Säugetiere. Springer Verlag, Berlin (DE), 322 pp.

Thewissen JGM 1985. Cephalic evidence for the affinities of Tubulidentata. Mammalia49(2), 257–284. DOI: https://doi.org/10.1515/mamm.1985.49.2.257

Darwinism's failure as a predictive model XX

Darwinism's Predictions 

Cornelius G Hunter 

fundamental premise of evolutionary theory is that evolution has no foresight. It is a blind process responding to current, not future, needs. This means that biological structures do not evolve before they are needed. But many examples of this have been discovered in recent years. For instance, in the embryonic stages of a wide variety of organisms, the development of the vision system is orchestrated by similar control genes known as transcription factors. As one paper explained, “All eyes, invertebrate and vertebrate, develop through a cascade of similar transcription factors despite vast phylogenetic distances.” (Wake, Wake and Specht) Because these transcription factors are so prevalent across the evolutionary tree, they must have evolved in the very early stages of evolution, in an early common ancestor. But that was before any vision systems had evolved. The vision system is just one of several such examples showing that the genetic components of many of today’s embryonic development pathways must have been present long before such pathways existed. Evolutionists now refer to the appearance of these genetic components, before they were used as such, as preadaptation:

 Genome comparisons show that the early clades increasingly contain genes that mediate development of complex features only seen in later metazoan branches. … The existence of major elements of the bilaterian developmental toolkit in these simpler organisms implies that these components evolved for functions other than the production of complex morphology, preadapting the genome for the morphological differentiation that occurred higher in metazoan phylogeny. (Marshall and Valentine) 

Such preadaptation extends beyond embryonic development. For example, several key components of the human brain are found in single-celled organisms called choanoflagellates. Therefore these key components must have evolved in single-celled organisms, long before animals, brains and nerve cells existed. As one evolutionist explained, “The choanoflagellates have a lot of precursors for things we thought were only present in animals.” (Marshall)

 

Another example is the molecular machines for protein transport across the mitochondria inner membrane which must have evolved long before mitochondria existed. (Clements et. al.) As one evolutionist explained, “You look at cellular machines and say, why on earth would biology do anything like this? It’s too bizarre. But when you think about it in a neutral evolutionary fashion, in which these machineries emerge before there’s a need for them, then it makes sense.” (Keim) 

References 

Clements, A., D. Bursac, X. Gatsos, et. al. 2009. “The reducible complexity of a mitochondrial molecular machine.” Proceedings of the National Academy of Sciences 106:15791-15795.

 

Keim, Brandon. 2009. “More ‘Evidence’ of Intelligent Design Shot Down by Science.” Wired Aug. 27. http://www.wired.com/wiredscience/2009/08/reduciblecomplexity/

 

Marshall, Michael. 2011. “Your brain chemistry existed before animals did.” NewScientist September 1.

 

Marshall C., J. Valentine. 2010. “The importance of preadapted genomes in the origin of the animal bodyplans and the Cambrian explosion.” Evolution 64:1189-1201.

Wake D., M. Wake, C. Specht. 2011. “Homoplasy: from detecting pattern to determining process and mechanism of evolution.” Science 331:1032-1035.