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India's Pig

Fig. 1 Digital texture. Adobe Photoshop

How could a small deer-like artiodactyl be related to the largest animal ever


Indohyus, meaning "India's pig" is thought to be the oldest relative of whales. Discovered in  Eocene deposits of the Himalayas, this small animal was once thought to be a distant relative of pigs. The original fossils were discovered by Ranga Rao in 1971 in the Dehra Dun region of India. As a side note, George Harrison recorded a song about this area. 

Rao died before completely describing the fossil material and it seemed the secerets of "India's pig" were buried along with him. But in 2007, Rao's widow gave the fossils to legendary anatomist Dr. Hans Thewissen to analyze.

By accidentally breaking the cranium, Dr. Thewissen discovered Indohyus had the same ear bones as do all modern and extinct whales. This meant that the racoon-sized Indohyus was in the whale family tree. It is rare fossil discoveries like this that have lead scientists to piece together the whale evolutionary lineage. The fact so many rare cetacean fossils have been found in the right place at the right time is unique in the history of evolutionary discoveries. Further analysis of Indohyus revealed it was actually thick boned (osteosclerotic), which also meant it was fully aquatic. Perhaps this allowed the animal to leap in the water to evade predators, much like modern chevrotains do.

 

How I Did It

Understanding that Indohyus could've been nocturnal, much like chevrotains, I wanted to create a night scene for this reconstruction. After making a few quick drawings, I decided on this pose (Fig. 2)  because it showed off the most notable anatomical features of the animal: The long face and long hoofed limbs. Additionally, it presented an opportunity to showcase a bit of inferred behavior.

Fig. 2 Graphite, oil, & ballpoint pen on paper. 

Once I had the right pose drawn out, I scanned the drawing and layered digital fur(Fig. 3).  Once I had the whole animal textured, it was time to work on the background.

Fig. 3 Fur texture detail

Fig. 3 Fur texture detail

I began with a perspective layout matching the rough drawing (Fig4). This would serve as the foundation for forest texture (Fig. 5). 

Fig. 4 Digital layout in Adobe Photoshop.

Fig. 5 Background texturing process

It was then a matter of compositing Indohyus into the background. This part was a little bit tricky because I had to match the light source and darken appropriate areas. Too much dark would obscure the fur details and too little contrast would remove visual emphasis. After experimenting with a few levels, I settled on a balanced look. 

Fig. 6

I wasn't too satisfied with the red tint because it didn't convey the colors of night. I changed the hue and felt it was a more proper fit for the scene. 

Fig. 7 Indohyus in its new home

 

References

Bajpai, S; Thewissen, JG; Sahni, A (November 2009). "The origin and early evolution of whales: macroevolution documented on the Indian subcontinent". J Biosci. 34 (5): 673–86. doi:10.1007/s12038-009-0060-0. OCLC 565869881. PMID 20009264

Rao, A Ranga (1971). "New mammals from Murree (Kalakot Zone) of the Himalayan foot hills near Kalakot, Jammu and Kashmir state, India". Journal of the Geological Society of India. 12 (2): 124–34.

Sample, Ian. "How Bambi Evolved into Moby-Dick." The Guardian.com. N.p., 19 Dec. 2007. Web. <https://www.theguardian.com/science/2007/dec/19/whale.deer?gusrc=rss&feed=networkfront>.

 

 

 

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When Whales Walked

Fig. 1   Graphite, ballpoint pen and oil on paper. 


Natural History

Ambulocetus natans was an early whale ancestor capable of moving on land and underwater.  Named from an almost complete skeleton from Pakistan, A. natans was sea lion-sized and likely ambushed its prey. Since it did not have a tail fluke, this amphibious cetacean ancestor used its prominent hind limbs as oars to propel itself underwater. Its dense limb bones(osteosclerotic) tells us that it moved well in estuarine habitats, but was probably clumsy on land. Its face was long, and crocodile-like, with eyes set dorsally and probably fed by drowning larger prey. 

It was an important discovery in piecing together the cetacean family tree, as it showed how whales went from "land-lubbers" to blubber-laden fully aquatic ecomorphs.

How do we know it was a whale? The one feature that consistently unites whales and their kin are the ear bones (auditory bullae) and A. natans is no exception. Analysis of its ear reveals that Ambulocetus heard well underwater.

 

How I Did It

I wanted to show Ambulocetus in its element using the latest science. I began with a rough gesture drawing (Fig. 1) to which I then added digital textures in Photoshop. To understand the surface anatomy better, I created a muscle reconstruction (Fig. 2). 

Fig. 2  Color pencil & ballpoint pen on paper; digital colorization in Adobe Photoshop.

Understanding of the musculature allowed me to work out lighting over the forms better. Although the coat pattern of Ambulocetus is speculative, I was inspired to use facial markings similar to those of modern whales. Lastly, I wanted to add very contrasted lighting for two reasons: 1.) to simulate the soft shadows seen in murky underwater photographs 2.) represent the former "mystery" of whale evolution and consequent "light" of discovery  brought about by Ambulocetus.

 

Fig. 3 The finished piece: Ambulocetus takes a lungfish prey

Fig. 3 The finished piece: Ambulocetus takes a lungfish prey

 

 

References

Kemp, T. S. (2005). The Origin and Evolution of Mammals (PDF). Oxford University Press. ISBN 0-19-850760-7. OCLC 232311794. Retrieved June 2016. 

Konami Ando, Shin-ichi Fujiwara, Farewell to life on land – thoracic strength as a new indicator to determine paleoecology in secondary aquatic mammals.

Thewissen et al. 2009, Ambulocetidae: the First Marine Cetaceans.

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Afrotherian Systematics

Early sketch for Afrotherian Systematics

Early sketch for Afrotherian Systematics

Once upon a time, (like pre-nineties) it was thought mammal orders were neatly compartmentalized groupings with clearly distinct ancestries. For example, it was common scientific belief all anteater-like mammals were related, all carnivorous mammals were a lineage, all hoofed mammals were another and so on, with not many complications to this pattern. However, new findings from evolutionary genetics have thrown a massive monkey wrench to the neat and tidy traditionalist taxonomic frame of  Linnean Classification. These molecular studies sometimes conflict with morphology perspectives, as in the case of whale evolution, but overall provide crucial insights where gaps in the fossil record exist. Afrotheria is one such revolutionary idea emerging from this flurry of new evolutionary research, but with increasing data in support, becomes more solidified in the standard evolutionary framework. 

Afrotheria: What Moles, Shrews, Elephants and Elephant Shrews Share

Afrotheria is an unique and ancient superorder of placental mammals first proposed in the late 1990's (Stanhope et al). It is also one of the oldest lineages of mammals to diverge. Chronological divergence estimates by Nishihara et.al using DNA transposable elements data indicate the three major supercohorts (Afrotheria, Boreotheria and Xenarthra) diverged nearly simultaneously in the Middle Cretaceous, right in the time of the non-avian dinosaurs.

 

Fig. 1 -A phylogenetic view of Afrotheria

Fig. 1 -A phylogenetic view of Afrotheria


Afrotheria consists of the basal members Ocepeia and Hyopsodontidae, and two clades, Afroinsectiphilia and Paengulata. Ocepeia is a hyrax-like mammal recently discovered in North Africa, and thought to be close to the ancestor of all Afrotherians while hyopsodontids were once part of that legendary “waste-basket” taxon Condylarthra. Hyopsodontids are thought to have been generalist early hoofed-mammals and thought to be omnivorous. Some like Hyopsodus were partially fossorial and one study even proposes a use of terrestrial echolocation by this taxon.

 

Fig. 2- Representative Afrotherians Vol. 1: 1. The Bibymalagasian Plesiorycteropus  2. The Ptolemaiid Ptolemaia 3. The Afredentate (?) Eurotamandua 4. The Embrythopod Arsinoitherium 5. The Desmostylian Paleoparadoxia

Fig. 2- Representative Afrotherians Vol. 1: 1. The Bibymalagasian Plesiorycteropus  2. The Ptolemaiid Ptolemaia 3. The Afredentate (?) Eurotamandua 4. The Embrythopod Arsinoitherium 5. The Desmostylian Paleoparadoxia

Fig. 3- Representative Afrotherians Vol. 2 :  5. Just another aardvark, Orycteropus 6. The golden mole, Chrysochloris 7. The tenrec Tenrec 8. The Macroscelid Rhyncocyon and 9. the hyrax Procavia.   

Fig. 3- Representative Afrotherians Vol. 2 :  5. Just another aardvark, Orycteropus 6. The golden mole, Chrysochloris 7. The tenrec Tenrec 8. The Macroscelid Rhyncocyon and 9. the hyrax Procavia.   


Afroinsectiphilia carries the orders Macroscelidae (Elephant shrews), Afosoricida(moles, tenrecs and "regular" shrews) and Tubulidentata (Aardvarks), with possible inclusion of the extinct orders Bibymalagasia (Plesiorycteropus, enigmatic Malagasy mammal), Ptolemaiida and Afredentata (the infamous Eurotamandua). Something to note: African golden moles, under this premise, are not closely related to other moles and are similar due to convergent evolution. Additionally, the placement of Eurotamandua within Afrotheria is still highly controversial, and I have not found much information on this. Previously classified as an anteater, then pangolin, the relationships of Eurotamandua are still subject to change even though we have a complete skeleton in great preservation state.  The inclusion of Bibymalagasia, Ptolemaiida and Afredentata is still tentative and subject to further evidence. As an interesting side note, affinities between Afrotherians and South American hoofed mammals known as Meridungulates have been considered (Agnolin et al.) based on vertebral count, knee anatomy and tooth replacement patterns. Now this makes sense (remember how Africa and S.America fit together perfectly?) but I'd like to see more research on this topic. God, how I'd love to see more research on this topic.

Paengulata group together orders Hyracoidea(Hyraxes), Proboscidae (Elephants and allies), Sirenia (Sea Cows) and the extinct Desmostylia and Embrithopoda (see fig. 2).  Suffice it to say right now that Desmostylians are another highly intriguing group of large hoofed mammals that had amphibious anatomy, protruding incisors, and so many other neat anatomical feature. To put a modern analogy, think something like a beach hippo, but totally different. Bizarrely, Cooper et al have even proposed that Desmostylians are tentative perissodactyls. Embrithopods are another fascinating group that resemble a rhinoceros on steroids, although both lineages are not closely related. 

Back to Ocepeia. Within Afrotheria Ocepeia is reconstructed as more closely related to insectivore-like Afroinsectiphilians (i.e., aardvarks, sengis, tenrecs, and golden moles) than to Paenungulates.  One of the highly interesting features of the Ocepeia skull is the “character mosaic” nature of it; it represents the first known “transitional fossil between insectivore-like and ungulate-like Afrotherians”. The family Ocepeiidae supports the idea Afrotheria evolved in the either the earliest Tertiary or latest Cretaceous, making it one of the oldest lineages of mammals. This simultaneously knocks down hypotheses rooting the individual afrotherian lineages in Condylarth lineages of Paleogene Laurasia.

 

As previously mentioned, research into Afrotherian systematics is dismembering Condylarthra, and another group libreated in this taxonomic carnage is the family Hyopsodontidae, consisting of a few not-very specialized small taxa. The idea of Hyopsodontidaeas stem Afrotherians is rather new. Randolphe et al have proposed Eocene paenungulates and elephant-shrews are to be related to some Early Tertiary Euramerican ‘hyopsodontid condylarths. Like Ocepeia, these creatures evolved right after the KT boundry, when there was a wealthof niches available for mammals to exploit. The relationship between Ocepeia and hypsodontids awaits further fossil elucidation, but it does appear they are both close to the ancestor of all Afrotherians. The study also reports of cranial and dental evidence of Eocene stem hyrax and macroscelid from North Africa supporting Afrotheria. The publication was a seminal milestone in understanding the relationships of this amazing assortment of animals. Another interesting tidbit thrown out by the paper is that of possible Ptolemaiida affinities with Tubulidentata.

 

Bibymalagsia is the order that has only one member currently, the The ‘Malagasy aardvark’ (Plesiorycteropus).  Found in Madagascar, this mysterious creature (the other more mysterious taxon right off the top of my head is Necrolestes from South America) was written off as “just another aardvark (Orycteropus), but bigger” until Buckley  released a comprehensive study on the taxon.  A complete skull has not been recovered, with only cranial fragments providing the only information on that region but with sufficient post-cranial material to work with. Buckley has challenged  Plesiorycteropus's  affinities with Tubulidentates on the grounds that similarities with Orycteropus are based on convergence, not shared ancestry: both genera show adaptations for digging lifestyles. Plesiorycteropus’s skeletal anatomy shows diagnostic traits of several different eutherian mammalorders as well and thus cannot be placed in any existing taxon. The Buckley paper also includes the first ever molecular data for the genus, “obtained from the bone protein collagen (I), which places the ‘Malagasy aardvark’ as more closely related to tenrecs than aardvarks. More specifically, Plesiorycteropus was recovered within the order Tenrecoidea (golden moles and tenrecs) within Afrotheria, suggesting that the taxonomic order ‘Bibymalagasia’ is obsolete.” This indeed means Plesiorycteropus is not just “another big aardvark” buta very large semi-mole insectivorous lipotyphyan. Holy shit! For the time being, though, the existence of Bibymalagasia as a taxon remains as we await new findings.

Works Cited

Agnolin, F. L., &amp; Chimento, N. R. (2011). Afrotherian affinities for endemic South American “ungulates”. Mammalian Biology-Zeitschrift für Säugetierkunde, 76(2), 101-108.

Buckley, M. 2013: A molecular phylogeny of Plesiorycteropus reassigns the extinct mammalian order ‘Bibymalagasia’. PLoS ONE, 8(3): e59614. doi: 10.1371/journal.pone.0059614

Cooper, L. N.; Seiffert, E. R.; Clementz, M.; Madar, S. I.; Bajpai, S.; Hussain, S. T.; Thewissen, J. G. M. (2014-10-08). "Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls". PLoS ONE 9 (10): e109232. doi:10.1371/journal.pone.0109232

Gheerbrant, Emmanuel; Amaghzaz, Mbarek; Bouya, Baadi; Goussard, Florent; Letenneur, Charlène; (2014). "Ocepeia (Middle Paleocene of Morocco): The Oldest Skull of an Afrotherian Mammal". PLoS ONE 9 (2): e89739. doi:10.1371/journal.pone.0089739

Horovitz, Inés, Gerhard Storch, and Thomas Martin (2005). "Ankle structure in Eocene pholidotan mammal Eomanis krebsi and its taxonomic implications". Acta Palaeontol. Pol. 50 (3): 545–548

Nishihara, H.; Maruyama, S.; Okada, N. (2009). "Retroposon analysis and recent geological data suggest near-simultaneous divergence of the three superorders of mammals". Proceedings of the National Academy of Sciences 106 (13): 5235. doi:10.1073/pnas.0809297106

Rodolphe Tabuce et al. (2007) Early Tertiary mammals from North Africa reinforce the molecular Afrotheria clade.

Seiffert, Erik R.; (2007). "A new estimate of afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence".BMC Evolutionary Biology, 7:224doi:10.1186/1471-2148-7-224

Stanhope, M. J.; Waddell, V. G.; Madsen, O.; de Jong, W.; Hedges, S. B.; Cleven, G. C.; Kao, D.; Springer, M. S. (1998). "Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals". Proceedings of the National Academy of Sciences 95 (17): 9967–9972. doi:10.1073/pnas.95.17.9967. PMC 21445. PMID 9707584

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