YING YANG: ZYCHASPISES

Zenaspis pololica

A Devonian bony fish mortality plate showing a lower shield of Zenaspis podolica (Lankester, 1869) from Lower Devonian deposits of Podolia, Ukraine.

While war rages on in the Ukraine, our hearts go out to those who live and work here contributing much to our understanding of Podolia, a historic region in Eastern Europe, located in the west-central and south-western parts of Ukraine, in northeastern Moldova. 

As I write this, thousands of Ukrainians are arriving at the Palanca border crossing in Moldova on Ukraine's western border to escape the fighting and pincher advance of the Russian military in the north, south and east. 

Looking at a map of the Ukraine, I imagine a torch touching the edges that mental map alighting it with flame — the edges slowly burning and curling in as the world watches and good people on both sides feel that burn.

We look to the Ukraine with our modern lens as we are want to do. Ukraine emerged as the concept of a nation and the Ukrainians as a nationality with the Ukrainian National Revival in the mid-18th century, in the wake of the peasant revolt of 1768-1769 and the eventual partition of the Polish–Lithuanian Commonwealth. They have known a tense love/hate relationship with their neighboring nations for a long while, sharing culture and language but desiring freedom and independence. 

It became an independent state in 1991 with the collapse of the Soviet Union. This fertile part of the world has an archaeology record of human habitation that goes back to the first millennium BC — the oldest known main inhabitants of Ukraine were Cimmerians. They were replaced in Fifth Century BC by Scythians who ruled till 2nd Century BC. The Sarmatian tribes replaced them. Wars, battles and skirmishes ensued until the tribesmen of the dominant horde, the Alanis, could be said to rule in the First Century AD. While our recorded history, our ancestors likely hunted and past through here far earlier. 

Beneath our human habitation and current military action is bedrock that tells the story of the Earth's violent past. The fauna here are from the Silurian and record a time in our Earth's history where the planet suffered a major mass extinction event that wiped out 23 percent of all marine life. It is the only region in Ukraine where 420 million-year-old remains of ichthyofauna can be found near the surface, making them accessible to collection and study. 

Zenaspis is an extinct genus of jawless fish which thrived during the early Devonian. Being jawless, Zenaspis was probably a bottom feeder, dining on debris from the seafloor similar to how flounder, groupers, bass and other bottom-feeding fish make a living.

For the past 150 years, vertebrate fossils have been found in more than 90 localities situated in outcrops along banks of the Dniester River and its northern tributaries, and in sandstone quarries. 

At present, the faunal list of Early Devonian agnathans and fishes from Podolia number seventy-two species, including 8 Thelodonti, 39 Heterostraci, 19 Osteostraci, 4 Placodermi, 1 Acanthodii, and 1 Holocephali (Voichyshyn 2001a).

In Podolia, the Lower Devonian Redbeds strata (the Old Red Formation or Dniester Series) are 1800 metres thick and range from Lochkovian to Eifelian in age (Narbutas 1984; Drygant 2000, 2003).

In their lower part, the Ustechko and Khmeleva members of the Dniester Series are built from lovely multicoloured, mainly red, fine-grained cross-bedded massive quartz sandstones and siltstones with seams of argillites (Drygant 2000).

We see fossils of Zenaspis in the early Devonian of Western Europe. Both Zenaspis pagei and Zenaspis poweri can be found up to 25 centimetres long in Devonian outcrops of Scotland.

Reference: Voichyshyn, V. 2006. New osteostracans from the Lower Devonian terrigenous deposits of Podolia, Ukraine. Acta Palaeontologica Polonica 51 (1): 131–142. Photo care of the awesome Fossilero Fisherman, a fossil hunter devoted to collecting the Lower Devonian Creek exposures of the Ukraine