The bambis, part 3: smallest of all deer vs smallest of all bovids

...continued from https://www.inaturalist.org/journal/milewski/55475-the-bambis-part-2-diminutive-deer-of-the-americas#

The smallest species of deer (Pudu mephistophiles, https://en.wikipedia.org/wiki/Northern_pudu), like the smallest species of bovid (Neotragus pygmaeus, https://en.wikipedia.org/wiki/Royal_antelope), has adult female body mass less than 6 kg, has horn-like organs in males only, bears one unspotted infant at a time, and eats mainly foliage.

However, these bambis differ in significant ways.

Females weigh 1.5 kg more in Pudu mephistophiles than in Neotragus pygmaeus. This may be partly explained by a difference in climates: the deer lives high and cold in the Andes, whereas the bovid lives close to sea level in perennial warmth. The deer has thick, coarse, brittle fur and furry ear pinnae, whereas the bovid has short, fine fur and bare ear pinnae.

Pudu mephistophiles has small eyes and large ears, whereas the converse is true for Neotragus pygmaeus. The eyes are also placed more laterally in the bovid (https://www.mindenpictures.com/stock-photo-royal-antelope-neotragus-pygmaeus-adult-female-close-up-of-head-naturephotography-image80076754.html) than in the deer.

Pudu mephistophiles sheds and regrows its relatively long antler-spikes each year, whereas the short horn-spikes of Neotragus pygmaeus are permanent. This maintains a fundamental difference between deer and bovids despite the extreme reduction of the antlers.

Pudu mephistophiles has short legs, whereas Neotragus pygmaeus has long legs, the difference being mainly in the metacarpal and metatarsal bones. The deer has loose hooves and long dewclaws and is reputed to be able to climb logs and woody plants.

By contrast the bovid remains fully unguligrade despite its extreme lightness, and is one of the few artiodactyls lacking dewclaws.

There is a particularly remarkable difference reproductively. Newborns of the deer are extremely small (0.4 kg at maternal body mass up to 5 kg, = 8%) whereas those of the bovid are extremely large (0.8 kg at maternal body mass 0.3 kg, =27%).

This is true despite the gestation of the deer being one month longer than that of the bovid. The minimal maternal investment of Pudu mephistophiles is all the more anomalous considering that, like other deer, it has four teats.

The differences can be largely explained by different predatory pressures. The Andes are globally extreme in the abrupt ascent of this extremely narrow range of mountains from an otherwise low-lying continent.

Pudu mephistophiles thus lives in an archipelago-like geographical setting at remote altitudes.

By contrast Neotragus pygmaeus survives a naturally intense regime in which African carnivores are both diverse and common. Furthermore, the typical habitat of the deer is natural vegetation whereas that of the bovid is weedy regeneration after clearing by humans, who have long been major predators in our own right.

The large, laterally-placed eyes, elongated feet and tiny hooves, and extremely precocial offspring of Neotragus pygmaeus can all be interpreted as anti-predator adaptations.

The photographic record of Pudu mephistophiles is surprisingly poor, but I link all the photos I have found on the Web.

https://www.corbidi.org/uploads/4/9/8/9/49890817/feb2010_escamilo_barrio_et_al_ch13_neotropical_cervidology.pdf

https://www.academia.edu/2403466/CHAPTER_13_NORTHERN_PUDU_Pudu_mephistophiles_De_Winton_1896_

https://www.corantioquia.gov.co/ciadoc/FAUNA/AIRNR_CN_4718_2003.pdf

https://en.wikipedia.org/wiki/Northern_pudu#/media/File:Pudu_mephistolephis.png

https://fundaciongaloplazalasso.org/en/english-pudu-rescue-kind-of/

https://synapsid-taxonomy.tumblr.com/post/633754501583618049/pudu-mephistopheles-de-winton-1896

Neotragus pygmaeus

https://www.researchgate.net/publication/311546156_Neotragus_pygmaeus_Royal_Antelope

http://www.ultimateungulate.com/Artiodactyla/Neotragus_pygmaeus.html

https://www.ivis.org/library/comparative-placentation/royal-antelope-neotragus-pygmaeus

https://fuckyeahungulates.tumblr.com/post/22934424803/royal-antelope-calf-neotragus-pygmaeus