Since many members of the therian community are too young to remember these (or maybe you just never heard of them), I thought I'd make a post about what they even were.
Serious Therianthropy Discussion Chats or "STDCs" were events organized by the now-defunct website WereSource.
As you can read on the Therian Wikia, WereSource was an online Therian community, much like what Therian Guide is today. It was centered around the idea of gathering all of the Therian techy people, programmers and stuff. Think of the "source" part as "open source", whereas "were" was the word once commonly used to mean "Therianthropy".
WereSource's main cool feature was their IRC chat. IRC is... a program used for chat that is very similar to Discord today (Discord was modeled after IRC), except you could have your own server independent of any corporation somewhere on the Internet. And of course there was no voice. But IRC was very universal back in the day, "IRC" basically stands for Internet (relay) Chat.
Anyway, on this chat where everybody hung out and talked, the guys at WereSource thought to do a bi-weekly event, where people would get together and have a more structured, serious conversation about Therianthropy. They named these events aptly: "Serious Therianthropy Discussion Chats".
Since the WereSource website is offline now, I've used the WayBackMachine to recover some of their chat logs, where you can see what a STDC was like, here named after the different dates of the individual events:
25th of January 2009
2nd of February 2009
22nd of March 2009
28th of March 2009
10th of May 2009
It was organized by WereSource owner, TerrorWolf (a wolf therian), assisted by his two friends Pastedos and WolfFriend (dog therians as I recall). The rules for the chats were put down as follows:
Quote:<WolfFriend> We will be starting now
<WolfFriend> If you want to continue intro discussion, take it to PM, please
<WolfFriend> Welcome to the serious therianthropy discussion
<WolfFriend> We will keep this moderated while we describe the rules
<WolfFriend> Pastedos will lay them out for us shortly
<Pastedos> Let me just uhh, reference my notes
<WolfFriend>
<WolfFriend> (Sorry, it's been a couple weeks so I don't have it offhand)
<Pastedos> Ok, again thank you all for coming
<Pastedos> the following are the rules that we use for the discussion
<Pastedos> 1) If you have any questions please ask myself, WolfFriend, or Terrorwolf
<Pastedos> 2) Please do not spam the channel with off-topic stuff -- Take it to PM
<Pastedos> 3) When we introduce the topic at the start, we will be voicing/unvoicing participants so they may give cursorary discussions on the topic
<Pastedos> if you would like to speak, please PM myself, WolfFriend, or Terrorwolf and we will voice you so you may say your part
<Pastedos> After we have detailed the conversation enough, it will be open for a full discussion
<Pastedos> Each person will have 5 minutes
<Pastedos> Each discussion will be 30 minutes in length
<Pastedos> open sessions after each topic are 15 minutes
<Pastedos> Do we have any questions?
The "voicing" and "moderation" they speak of were mechanisms to give only individual people permission to post messages in chat at any one time. The staff would ask the questions and moderate the discussion.
I was around WereSource when these STDCs happened and was always very interested, however they usually ocured in a time of day that was like 4 am for me (here in Europe) and I couldn't ever really attend. We discussed changing the time, but it was most convenient for most of them so they couldn't change it.
Now this, as you can see, was over 10 years ago.
We've recently spoken of reviving the STDCs here on TG, however after thinking things through given how the times (and the technology) have changed, we've merged it with a Therian Radio talk show idea, and made it to be what you know now as Therian Talks.
Our friends over at the Werelist however, are thinking of bringing STDCs back in their original format. I'll say more about this when the idea is further along, but we will be relaying the STDCs into the Therian Guide Discord (room #stdc under "Creativity & Games"), so you will be able to follow it from here. 
LP,
Dusty