function GetNewestFile(dir: string): string;
var
  F: TSearchRec;
  Time: Integer;
begin
  dir := IncludeTrailingPathDelimiter(dir);
  Time := 0;
  Result := '';

  if FindFirst(dir + '*.*', faAnyFile, F) = 0 then
  try
    repeat
      if (F.Name <> '.') and (F.Name <> '..') and ((F.Attr and faDirectory) <> faDirectory) then
      begin
        if F.Time > Time then
        begin
          Result := F.Name//+ExtractFileExt(F.Name); habe angenommen so würde es funktionieren, tut es aber nicht :)
          Time := F.Time
        end;
      end;
    until FindNext(F) <> 0;
  finally
    FindClose(F);
  end;
end;