Ablative absolute?

[Matthaeus]

Audito siquidem, Casimirum revixisse, immo cum duce Laodimiriae Romano et principe Belsiae Wsewlodo comminus imminere, noctis compendio fugam ineunt Mesconidae.

Am I right in assuming that audito is an ablative absolute introducing the noun clause Casimirum revixisse ... imminere? I'm understanding this as something like audito (hoc) nuntio, etc... Not sure I've ever encountered an AA clause containing just one word. Is this rather uncommon in CL, or in other periods as well?

 

[Pacifica]

Am I right in assuming that audito is an ablative absolute introducing the noun clause Casimirum revixisse ... imminere? I'm understanding this as something like audito (hoc) nuntio, etc... Not sure I've ever encountered an AA clause containing just one word.

You've got an ablative absolute there, yes.
Technically, the clause functions as the subject of the ablative absolute (the clause is what was heard), so the ablative isn't really "just one word", though I see why you said that (only one word is a simple ablative).

Is this rather uncommon in CL, or in other periods as well?

I'm not sure Cicero would have done it, but I've definitely seen it in some ancient historian or historians. I don't remember which; it could have been Livy and/or Tacitus, possibly others.

 

[Pacifica]

I've definitely seen it in some ancient historian or historians. I don't remember which; it could have been Livy and/or Tacitus, possibly others.

I searched PHI and found the construction in Sallust, Livy and (most often) Tacitus:

Gaius Sallustius Crispus, Ad Caesarem de Re Publ. [sp.] 5.1.1 (packhum.org)

Titus Livius, Ab Urbe Condita 31.39.1.1 (packhum.org)
Titus Livius, Ab Urbe Condita 33.5.1.1 (packhum.org)

Cornelius Tacitus, Historiae 4.36.1 (packhum.org)
Cornelius Tacitus, Historiae 1.66.1 (packhum.org)
Cornelius Tacitus, Historiae 2.60.1 (packhum.org)
Cornelius Tacitus, Historiae 4.36.1 (packhum.org)
Cornelius Tacitus, Historiae 4.62.1 (packhum.org)
Cornelius Tacitus, Historiae 11.13.1 (packhum.org)
Cornelius Tacitus, Historiae 14.57.1 (packhum.org)

Also in Gellius and Apuleius:

Aulus Gellius, Noctes Atticae 1.13.pr.1 (packhum.org)
Apuleius Madaurensis, Metamorphoses 1.1.1 (packhum.org)

That's only for the word comperto; it also happens with words of similar meaning such audito and cognito. I'm not going to dig up all the examples, but here are two in Tacitus:

Cornelius Tacitus, Historiae 2.7.1 (packhum.org)
Cornelius Tacitus, Historiae 1.46.1 (packhum.org)

(He seems to prefer comperto, though.)

 

[Matthaeus]

Thanks for the clarification!