Eric Shipton yeti snowprint revisited

So odd, so different,
it might just be real. It all started with a photograph by Eric Shipton from decades ago of a single large footprint in the snow of the Himalayan Mountains (Fig. 1). Here I simply added bones based on the apparent primate nature of the trackmaker and included gorilla pedal data for comparison.

Figure 1. Eric Shipton snowprint of Yeti with hypothetical bones and PILs applied. At top is pes of Gorilla. Ice pick for scale.

Figure 1. Eric Shipton snowprint of Yeti with hypothetical bones and PILs applied. At top is pes of Gorilla. Ice pick for scale. The impressions of digits 2 and 3 indicate logical interpretation with toe drag to avoid broken toe /#2 and nussubg toe #3 impression.

Distinct from human tracks,
the big toe of the Himalayan trackmaker is much bigger and does not extend as far as in humans. The tracks is wider than in humans. Digit 2 appears to be shorter than in humans.

Several years ago an expert of yeti and bigfoot, Dr. Jeff Meldrum,
appeared on ‘Joe Rogan Questions Everything’ #2 with Duncan Trussell (audio only, click to listen via YouTube). While Joe and Duncan tried to add levity to the discussion, Dr. Meldrum portrayed the facts as he knew them, keeping speculation to a minimum.

We touched on this subject
about a year ago earlier here.

Oreopithecus, a European ape at the center of yet another bipedal debate

During the Miocene (9–7mya)
the Italian peninsula, then reduced to a series of islands, was the jungle home to long-limbed apes like Oreopithecus (Figs. 1–3; Gervais 1872, 4 feet tall). This taxon has been at the focus of a bipedal/quadrupedal argument since the 1950s. (So have pterosaurs.) 

Huerzler 1949
considered this specimen, “the earliest known representative of the line that led to man.” The hand was capable of a precision grip, convergent with human ancestors. The relatively broad pelvis (Figs. 1–3) and short jaws with small canines and other teeth of Oreopithecus were once considered diagnostic for a place in the transition to human bipedality. 

Figure 1. Oreopithecus in situ traced with colors. This fossil is imperfectly preserved and the skull is crushed like an eggshell.

Figure 1. Oreopithecus in situ traced with colors. This fossil is imperfectly preserved and the skull is crushed like an eggshell. Some bones are easy to identify. Others are best guesses.  See figure 2 for the reconstruction. This is the Hürzeler 1949 specimen.

Other workers have disputed this.
Oreopithecus was considered a jungle/swamp dweller with adaptations for hanging by its long arms from overhead branches. Gibbons have not yet been tested in the LRT, but the size and proportions appear similar.

Figure 2. Tentative reconstruction of elements traced in the Oreopithecus in situ figure 1. Other elements added from other authors.

Figure 2. Tentative reconstruction of elements traced in the Oreopithecus in situ figure 1. Other elements attributed to Oreopithecus added from other authors. Due to disarticulation and/or loss, finger and toe bones are guesswork.

While the hand and pelvis proportions
(Fig. 3) were similar to those of hominins (humans and their bipedal kin), the foot (Fig. 2, from another specimen) definitely was not. This indicates convergence, which remains rampant within the LRT.

Oreopithecus has not yet been added to the LRT.

Figure 3. From Rook et al. 1999 comparing an Oreopithecus ilium to that of Homo and Hylobates.

Figure 3. From Rook et al. 1999 comparing an Oreopithecus ilium to that of Homo and Hylobates.

Carbon isotopes
suggest a diet of “energy-rich underground tubers and corms, or even aquatic vegetation,” according to Nelson 2016. This is consistent with an arboreal yet swampy environment.

References
Gervais P 1872. Sur un singe fossile d’un espèce non ancore décrite, qui a été découvert au monte Bamboli. Comptes Rendues de l’Académie des Sciences Paris, 74: 1217-1223.
Harrison T 1990. The implications of Oreopithecus for the origins of bipedalism, in Coppens, Y; Senut, B, Origine(s) de la Bipédie chez les Hominidés [Origin(s) of Bipedalism in Hominids.
Hürzeler J 1949. Neubeschreibung von Oreopithecus bambolii Gervais.- Schweizerische Palaeontologische Abhandlungen 66(5):1–20.
Köhler M and Moya-Sola S 2003. La evolución de Oreopithecus bambolii Gervais, 1872 (Primates, Anthropoidea) y la condición de insularidad. Coloquios de Paleontología, Vol. Ext. 1 (2003) 443-458.
Nelson SV 2016. Isotopic reconstructions of habitat change surrounding the extinction of Oreopithecus, the last European ape. American Journal of Physical Anthropology 160:254–271. https://doi.org/10.1002/ajpa.22970
Rook L, Bondioli L, Köhler M, Moya-Sola S and Macchiarelli R 1999. Oreopithecus was a bipedal ape after all: Evidence from the iliac cancellous architecture. Proceeding of the National Academy of Science USA 96:8795–8799.
Russo GA and Shapiro LJ 2013. Reevaluation of the lumbosacral region of Oreopithecus bambolii. Journal of Human Evolution, published online July 23, 2013; doi: 10.1016/j.jhevol.2013.05.004

wiki/Oreopithecus

Milwaukee Journal account of the Huerzeler Oreopithecus
Smithsonian Magazine account of Oreopithecus controversies
BBC account of Oreopithecus
SciNews account of Oreopithecus

European evolution

The attached video from YouTube
shows the changing boundaries and populations of various clades of Europeans and their invading neighbors evolving over a brief amount of time: only 2417 years. You’ll witness growth, death, aggression, expansion, division, union, stasis, invasion, decay and exploration.

In evolutionary terms, Europe is a petrie dish
and we who have ancestors that lived there with rising and falling fortunes. And there is no reason to suggest that things will never change in the future. Similar videos have appeared for Asia, the world, various words, etc. etc.

Things happen.
Weather changes. Volcanoes spew. Diseases decimate. People interbreed and emigrate. Languages change. So does DNA. Sometimes education is elevated. Sometimes religion is elevated. Sometimes slaves are imported. Sometimes slaves are freed. Sometimes autocrats run amok. Sometimes cooler heads prevail.

Somehow everyone living today
had an unbroken chain of ancestors going back to tetrapods in the Devonians, chordates in the Cambrian and worms in the Ediacaran and beyond. All of this is evolution at its finest, both short term (Fig. 1) and long.

Taxa closest to the human lineage in the LRT

The large reptile tree is capable of providing a list of taxa closest to the lineage of any included taxon. And it is updated all the time…

For instance,
in the lineage of humans (Homo sapiens) the following taxa are closest to that main line. Read this list with the understanding that taxa closest to the main line have often evolved traits that we infer (from phylogenetic bracketing) were not present in the actual hypothetical ancestor. The chance of finding the actual ancestors in the fossil record are vanishingly small, so we do the best we can with what specimens we have. Also note that the rare appearance of key fossils may be tens to hundreds of millions of years after their likely first appearance in this lineage. Thus the the chronological order may not match the phylogenetic order, but it does provide a ‘window’ to that first appearance.

  1. Ichthyostegabasal tetrapod  365 mya
  2. Pederpes 350 mya
  3. Proterogyrinus 322 mya
  4. Seymouria 275 mya
  5. Utegenia – also basal to frogs 300 mya
  6. Silvanerpetonproximal to the basalmost reptile 335 mya
  7. Gephyrostegus bohemicusbasalmost reptile/amniote 310 mya
  8. Eldeceeonbasalmost archosauromorph 335 mya
  9. Romeriscus 306 mya
  10. Solenodonsaurus also basal to chroniosuchids 290 mya
  11. Casineria – 335 mya
  12. Brouffia 310 mya
  13. Coelostegus  310 mya
  14. Protorothyris MCZ 1532 290 mya
  15. Protorothyris CM 8617 290 mya
  16. Protorothyris MCA 2149 290 mya
  17. Vaughnictis – last common ancestor of mammals and dinosaurs 290 mya
  18. Apsisaurus –  basalmost synapsid 295 mya
  19. Varanosaurus FMNH PR 1760 280 mya
  20. Varanosaurus BSPHM 1891 XV20 280 mya
  21. Archaeothyris 306 mya
  22. Ophiacodon 290 mya
  23. Haptodus – also basal to pelycosaurs 305 mya
  24. Stenocybus – also basal to anomodontids 295 mya
  25. Cutleria basalmost therapsid 295 mya
  26. Hipposaurusbasalmost kynodont 260 mya
  27. Ictidorhinus 260 mya
  28. Biarmosuchus 260 mya
  29. Eotitanosuchus 260 mya
  30. Lycosuchus 260 mya
  31. Procynosuchusbasalmost cynodont 250 mya
  32. Thrinaxodon 245 mya
  33. Probainognathus 230 mya
  34. Haldanodon 145 mya
  35. Pachygenelus 195 mya
  36. Sinoconodonbasalmost mammal, also basal to living monotremes 195 mya
  37. Megazostrodon 200 mya
  38. Juramaia 160 mya
  39. Cronopio 98 mya
  40. Didelphisbasalmost metatherian extant
  41. Thylacinus – basal to many living marsupials recently extinct
  42. Monodelphisbasalmost eutherian extant
  43. Eomaia 125 mya
  44. Nandinia – also basal to carnivores extant
  45. Ptilocercus – basalmost primate/dermpteran/bat extant
  46. Notharctus – also basal to lemurs 54 mya
  47. Aegyptopithecus* 33 mya
  48. Proconsulbasalmost anthropoid 18 mya
  49. Ardipithecus* basalmost hominid 5 mya
  50. Australopithecus* 3 mya
  51. Homo sapiens extant

* not yet listed in the LRT, but documented at ReptileEvolution.com

With the recent addition of certain stem mammals,
like Haldanodon and Liaconodon, this list expands upon and refines the list that first appeared in Peters 1991. Each of the names links to further information. There is also a video that includes most of these taxa here on YouTube.com.

References
Peters D 1991. From the Beginning, the Story of Human Evolution. online PDF.

The human occiput and palate

We looked at the facial portion
of the human skull earlier. Today we’ll look at the occiput and palate (Fig. 1).

Figure 1. Human occiput and palate. On most tetrapods these two are usually set at right angles to each other, but an upright stance has rotated the occiput to a ventral orientation.

Figure 1. Human occiput and palate. On most tetrapods these two are usually set at right angles to each other, but an upright stance has rotated the occiput to a ventral orientation.

There’s nothing new here. 
This is just an opportunity to educate myself on the human palate and occiput. Only the endotympanic (En) is a novel ossification. The occiput is a single bone here, the product of the fusion of several occipital bones. Can you find the suborbital fenestra? It’s pretty small here.

The asymmetry is interesting here.
Sure, this is an old adult, missing some teeth, but you’ll see other examples elsewhere.

Let me know
if you see any errors and they will be corrected. As you already know, everything I present here was learned only 48 hours earlier — or less.

The vague persistence of ‘absent’ bones in the human skull

Humans
(genus: Homo) are, of course mammals, and basal mammals lose the postorbital bar found in cynodonts like Chiniquodon. But even that postorbital bar does not include two bones found in more basal therapsids, the postfrontal and postorbital. In Chiniquodon the postorbital bar is created by a process of the frontal meeting a process of the jugal.

So I was surprised to find
what appear to be vague apparitions that look like those lost bones in the frontal of the human skull. There are 17 frames in this animation (Fig. 1). The last one holds for five seconds and reveals where I think I see vague outlines of the the prefrontal, postfrontal and postorbital bones all fused to the frontals, which are themselves fused medially.

Figure 1. Labeled skull bones in Homo sapiens. The last frame appears to identify the lost prefrontal, postfrontal and postorbital bones last seen in our ancestors from the Permian.

Figure 1. Labeled skull bones in Homo sapiens. The last frame appears to identify the lost prefrontal, postfrontal and postorbital bones last seen in our ancestors from the Permian. Note the dislocated jaw articulation.

The last part of the postorbitals

to ‘disappear’ are the posterior processes, which seem to laminate to the cranial bones in several therapsids, including dinocephalians. But there is also a vague portion that appears on the duckbill platypus, Ornithorhynchus.

The prefrontals
were the last to fuse and so appear to be the easiest to see now. Like gills and a tail, humans retain the genes for these, but they get resorbed or fused during embryonic ontogeny.

There is a difference between losing a bone
and fusing a bone. Phylogenetically losing a bone is usually marked by a reduction to disappearance. Fusion is, well, fusion. And that can be more readily reversed.

The pterygoid and lateral sphenoid
are both bones typically seen in palatal view, but in mammals and humans they rise, tent-like, to appear in the nasal and orbital cavities.

In mammals the bones sometimes get new names
but they’re still the same bones. The jugal becomes the zygomatic arch, for instance. The bones that make up the occiput fuse to form the occipital.

We’ll look at the palate and occiput soon. 
And a fetus.

 

Basal hominid, fenestrasaur and archosaur analogies

When you look at the transition
from quadrupedal locomotion to bipedal locomotion in early hominids (Fig. 1), among many other details, you can’t help but be impressed by the increase in the relative length of the hind limbs.

Figure 1. When hominids became bipedal, their hind limbs became longer.

Figure 1. When hominids became bipedal, their hind limbs became much longer.

The same can be said
for the transition from semi-bipedal Cosesaurus (based on matching Rotodactylus tracks) to the fully bipedal Sharovipteryx (Fig. 2).

Figure 2. Cosesaurus was experimenting with a bipedal configuration according to matching Rotodactylus tracks and a coracoid shape similar to those of flapping tetrapods. Long-legged Sharovipteryx was fully committed to a bipedal configuration.

Figure 2. Cosesaurus was experimenting with a bipedal configuration according to matching Rotodactylus tracks and a coracoid shape similar to those of flapping tetrapods. Long-legged Sharovipteryx was fully committed to a bipedal configuration, analogous to hominids.

As in hominids,
freeing the fore limbs from terrestrial locomotion enabled fenestrasaurs to do something else, like flapping for secondary sexual displays, adding motion to their morphological ornaments. While the forelimbs were relatively smaller in Sharovipteryx, they were relatively larger in Bergamodactylus (Fig. 3) a long-legged basal pterosaur. There were no constraints on forelimb evolution in fenestrasaurs, analogous to theropod dinosaurs that ultimately became birds. Some theropods and birds grew larger forelimbs, while others reduced their forelimbs.

Figure 2. Updated reconstruction of Bergamodactylus to scale with an outgroup, Cosesaurus.

Figure 3. Updated reconstruction of Bergamodactylus to scale with an outgroup, Cosesaurus.

Lest we not forget
in the basal archosaurs (crocs + dinos) early attempts at bipedal locomotion (Fig. 3) also corresponded to a longer hind limb length in bipedal Scleromochlus and Pseudhesperosuchus as opposed to their common ancestor, a sister to short-legged Gracilisuchus.

Figure 3. Short-legged Gracilisuchus, along with sisters, long-legged bipedal Pseudhesperosuchus and Scleromochlus.

Figure 3. Short-legged Gracilisuchus, along with sisters, long-legged bipedal Pseudhesperosuchus and Scleromochlus.

Based on those tiny hands,
the forelimbs of Scleromochlus were becoming vestiges. Based on the long proximal carpals of Pseudhesperosuchus, the manus was occasionally lowered to the ground, perhaps while feeding. The origin of bipedal locomotion in basal crocs is the same as in pre-dinosaurs.

It took much longer and proceeded more indirectly
for bipedal archosaurs to start flapping their forelimbs, giving them a new use that ultimately produced thrust and lift as bird forelimbs continued to evolve and become larger.

See videos produced by ReptileEvolution.com
on the origin of dinosaurs here, on the origin of humans here, and on the origin of pterosaurs here.

A sign of beauty and/or Olympic potential
is a long-legged model or athlete.