Japanese Aorist?

I am beginning to think that Japanese has an Aorist-like tense in addition to the much-talked-about unmarked form vs. perfect. Compare the following pair.

I. 猫は/が、川を渡る。

1. neko-wa/ga kawa-o wataru.
2. cat-TOPIC/NOM river-ACC cross
   

II. 猫、川を渡る。

1. neko kawa-o wataru
2. cat river-ACC cross
   

Two sentences look the same but the former means, "The/A cat crosses the/a river" and the latter, "The/A cat crossed the/a river." The simple lack of postposition for the subject noun in the latter describes the action of the sentence as an objective event that happened in the past with little relationship to the present. This construction is often employed in newspaper titles. I would not consider it is far-fetched to see a phenomenon quite similar to what is called aorist in Indo-European syntax.

In fact, the two wataru's manifest morphological difference as below;
I' OK neko-wa/ga kawa-o wataru-yo.
II' * neko kawa-o wataru-yo.
where -yo adds to a sentence a spin to make the hearer take heed for a piece of new information. The whole sentence I' translates into, "Hey look, a cat crosses the river."

The aorist wataru cannot take a modality particle.